From a07484570f806a5d891d13ea33d616c804a72184 Mon Sep 17 00:00:00 2001
From: Mohamed Nazem <109486038+nazem0@users.noreply.github.com>
Date: Wed, 19 Aug 2026 15:07:18 +0300
Subject: [PATCH 01/17] feat: add IQueryable DTO projection support to
 read-only application services

---
 .../Services/AbstractKeyReadOnlyAppService.cs | 50 +++++++++++++++++--
 .../Services/ReadOnlyAppService.cs            | 11 +++-
 .../ObjectMapping/IQueryProjectionMapper.cs   |  8 +++
 .../ObjectMapping/QueryProjectionMapper.cs    |  7 +++
 4 files changed, 70 insertions(+), 6 deletions(-)
 create mode 100644 framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
 create mode 100644 framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs

diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
index 3791c4202f..0c53ac2705 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
@@ -44,6 +44,18 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected virtual string? GetListPolicyName { get; set; }
 
+    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? ObjectProjectionMapper =>
+        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetOutputDto>>();
+
+    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? ListProjectionMapper =>
+        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
+
+    protected virtual bool UseObjectProjectionMapper =>
+        ObjectProjectionMapper != null;
+
+    protected virtual bool UseListProjectionMapper =>
+        ListProjectionMapper != null;
+
     protected AbstractKeyReadOnlyAppService(IReadOnlyRepository<TEntity> repository)
     {
         ReadOnlyRepository = repository;
@@ -53,6 +65,19 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         await CheckGetPolicyAsync();
 
+        var projectionMapper = ObjectProjectionMapper;
+
+        if (UseObjectProjectionMapper && projectionMapper != null)
+        {
+            var query = await GetEntityByIdQueryAsync(id);
+
+            var dto = 
+                await AsyncExecuter.FirstOrDefaultAsync(projectionMapper.ProjectTo(query))
+                ?? throw new EntityNotFoundException(typeof(TEntity), id);
+
+            return dto;
+        }
+
         var entity = await GetEntityByIdAsync(id);
 
         return await MapToGetOutputDtoAsync(entity);
@@ -65,7 +90,6 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
         var query = await CreateFilteredQueryAsync(input);
         var totalCount = await AsyncExecuter.CountAsync(query);
 
-        var entities = new List<TEntity>();
         var entityDtos = new List<TGetListOutputDto>();
 
         if (totalCount > 0)
@@ -73,8 +97,19 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
             query = ApplySorting(query, input);
             query = ApplyPaging(query, input);
 
-            entities = await AsyncExecuter.ToListAsync(query);
-            entityDtos = await MapToGetListOutputDtosAsync(entities);
+            var projectionMapper = ListProjectionMapper;
+
+            if (UseListProjectionMapper && projectionMapper != null)
+            {
+                entityDtos = await AsyncExecuter.ToListAsync(
+                    projectionMapper.ProjectTo(query)
+                );
+            }
+            else
+            {
+                var entities = await AsyncExecuter.ToListAsync(query);
+                entityDtos = await MapToGetListOutputDtosAsync(entities);
+            }
         }
 
         return new PagedResultDto<TGetListOutputDto>(
@@ -85,6 +120,13 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected abstract Task<TEntity> GetEntityByIdAsync(TKey id);
 
+    protected virtual Task<IQueryable<TEntity>> GetEntityByIdQueryAsync(TKey id)
+    {
+        throw new NotImplementedException(
+            "Override this method to create the query used for getting an entity by id."
+            );
+    }
+
     protected virtual async Task CheckGetPolicyAsync()
     {
         await CheckPolicyAsync(GetPolicyName);
@@ -227,4 +269,4 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         return ObjectMapper.Map<TEntity, TGetListOutputDto>(entity);
     }
-}
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
index 867ca35ad4..0cfbdee673 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
@@ -37,7 +37,7 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
     protected IReadOnlyRepository<TEntity, TKey> Repository { get; }
 
     protected ReadOnlyAppService(IReadOnlyRepository<TEntity, TKey> repository)
-    : base(repository)
+        : base(repository)
     {
         Repository = repository;
     }
@@ -47,6 +47,13 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
         return await Repository.GetAsync(id);
     }
 
+    protected override async Task<IQueryable<TEntity>> GetEntityByIdQueryAsync(TKey id)
+    {
+        var query = await Repository.GetQueryableAsync();
+
+        return query.Where(e => e.Id.Equals(id));
+    }
+
     protected override IQueryable<TEntity> ApplyDefaultSorting(IQueryable<TEntity> query)
     {
         if (typeof(TEntity).IsAssignableTo<ICreationAuditedObject>())
@@ -58,4 +65,4 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
             return query.OrderByDescending(e => e.Id);
         }
     }
-}
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
new file mode 100644
index 0000000000..b40ea1c198
--- /dev/null
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
@@ -0,0 +1,8 @@
+using System.Linq;
+using Volo.Abp.DependencyInjection;
+namespace Volo.Abp.ObjectMapping;
+
+public interface IQueryProjectionMapper<TSource, TDestination> : ITransientDependency
+{
+    IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
new file mode 100644
index 0000000000..96e9c98c3a
--- /dev/null
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
@@ -0,0 +1,7 @@
+using System.Linq;
+namespace Volo.Abp.ObjectMapping;
+
+public abstract class QueryProjectionMapper<TSource, TDestination> : IQueryProjectionMapper<TSource, TDestination>
+{
+    public abstract IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
+}
\ No newline at end of file

From 9b371db770ae0b3865b2b93353e6cbfa07ee6900 Mon Sep 17 00:00:00 2001
From: Mohamed Nazem <109486038+nazem0@users.noreply.github.com>
Date: Wed, 19 Aug 2026 17:00:53 +0300
Subject: [PATCH 02/17] Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
---
 .../Volo/Abp/ObjectMapping/QueryProjectionMapper.cs              | 1 +
 1 file changed, 1 insertion(+)

diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
index 96e9c98c3a..95fd3b02dd 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
@@ -1,4 +1,5 @@
 using System.Linq;
+

 namespace Volo.Abp.ObjectMapping;
 
 public abstract class QueryProjectionMapper<TSource, TDestination> : IQueryProjectionMapper<TSource, TDestination>

From 2ce16a7bb8b2ca8612c37c87d7c36f3f6aab4b1e Mon Sep 17 00:00:00 2001
From: Mohamed Nazem <109486038+nazem0@users.noreply.github.com>
Date: Wed, 19 Aug 2026 17:06:57 +0300
Subject: [PATCH 03/17] GetEntityByIdQueryAsync : null check

---
 .../Volo/Abp/Application/Services/ReadOnlyAppService.cs         | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
index 0cfbdee673..eab432239c 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
@@ -51,7 +51,7 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
     {
         var query = await Repository.GetQueryableAsync();
 
-        return query.Where(e => e.Id.Equals(id));
+        return query.Where(e =>e.Id != null && e.Id.Equals(id));
     }
 
     protected override IQueryable<TEntity> ApplyDefaultSorting(IQueryable<TEntity> query)

From 98d54c33dca97ff382159d44444a229b05308b18 Mon Sep 17 00:00:00 2001
From: Mohamed Nazem <109486038+nazem0@users.noreply.github.com>
Date: Wed, 19 Aug 2026 17:08:24 +0300
Subject: [PATCH 04/17] space between namespace and usings

---
 .../Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs            | 1 +
 .../Volo/Abp/ObjectMapping/QueryProjectionMapper.cs             | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
index b40ea1c198..5fe9f955b8 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
@@ -1,5 +1,6 @@
 using System.Linq;
 using Volo.Abp.DependencyInjection;
+
 namespace Volo.Abp.ObjectMapping;
 
 public interface IQueryProjectionMapper<TSource, TDestination> : ITransientDependency
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
index 95fd3b02dd..23bfb21141 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
@@ -1,5 +1,5 @@
 using System.Linq;
-

+
 namespace Volo.Abp.ObjectMapping;
 
 public abstract class QueryProjectionMapper<TSource, TDestination> : IQueryProjectionMapper<TSource, TDestination>

From 632addf8e84491c54cf4ca1a19cdac595403f214 Mon Sep 17 00:00:00 2001
From: Mohamed Nazem <109486038+nazem0@users.noreply.github.com>
Date: Wed, 19 Aug 2026 17:35:23 +0300
Subject: [PATCH 05/17] checking Use(Object/List)ProjectionMapper before
 resolving the mapper

---
 .../Services/AbstractKeyReadOnlyAppService.cs | 32 +++++++++++--------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
index 0c53ac2705..f70953b2ac 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
@@ -44,11 +44,9 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected virtual string? GetListPolicyName { get; set; }
 
-    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? ObjectProjectionMapper =>
-        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetOutputDto>>();
+    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? ObjectProjectionMapper { get; }
 
-    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? ListProjectionMapper =>
-        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
+    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? ListProjectionMapper { get; }
 
     protected virtual bool UseObjectProjectionMapper =>
         ObjectProjectionMapper != null;
@@ -59,20 +57,28 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     protected AbstractKeyReadOnlyAppService(IReadOnlyRepository<TEntity> repository)
     {
         ReadOnlyRepository = repository;
+
+        ObjectProjectionMapper =
+            LazyServiceProvider.LazyGetService<
+                IQueryProjectionMapper<TEntity, TGetOutputDto>>();
+
+        ListProjectionMapper =
+            LazyServiceProvider.LazyGetService<
+                IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
     }
 
     public virtual async Task<TGetOutputDto> GetAsync(TKey id)
     {
         await CheckGetPolicyAsync();
 
-        var projectionMapper = ObjectProjectionMapper;
-
-        if (UseObjectProjectionMapper && projectionMapper != null)
+        if (UseObjectProjectionMapper && ObjectProjectionMapper != null)
         {
             var query = await GetEntityByIdQueryAsync(id);
 
-            var dto = 
-                await AsyncExecuter.FirstOrDefaultAsync(projectionMapper.ProjectTo(query))
+            var dto =
+                await AsyncExecuter.FirstOrDefaultAsync(
+                    ObjectProjectionMapper.ProjectTo(query)
+                )
                 ?? throw new EntityNotFoundException(typeof(TEntity), id);
 
             return dto;
@@ -97,12 +103,10 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
             query = ApplySorting(query, input);
             query = ApplyPaging(query, input);
 
-            var projectionMapper = ListProjectionMapper;
-
-            if (UseListProjectionMapper && projectionMapper != null)
+            if (UseListProjectionMapper && ListProjectionMapper != null)
             {
                 entityDtos = await AsyncExecuter.ToListAsync(
-                    projectionMapper.ProjectTo(query)
+                    ListProjectionMapper.ProjectTo(query)
                 );
             }
             else
@@ -124,7 +128,7 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         throw new NotImplementedException(
             "Override this method to create the query used for getting an entity by id."
-            );
+        );
     }
 
     protected virtual async Task CheckGetPolicyAsync()

From e3f60c2a6ad958f257db59e208d4d4d4e855585a Mon Sep 17 00:00:00 2001
From: Mohamed Nazem <109486038+nazem0@users.noreply.github.com>
Date: Wed, 19 Aug 2026 18:19:20 +0300
Subject: [PATCH 06/17] revert : checking Use(Object/List)ProjectionMapper
 before resolving the mapper

---
 .../Services/AbstractKeyReadOnlyAppService.cs | 32 ++++++++-----------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
index f70953b2ac..0c53ac2705 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
@@ -44,9 +44,11 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected virtual string? GetListPolicyName { get; set; }
 
-    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? ObjectProjectionMapper { get; }
+    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? ObjectProjectionMapper =>
+        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetOutputDto>>();
 
-    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? ListProjectionMapper { get; }
+    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? ListProjectionMapper =>
+        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
 
     protected virtual bool UseObjectProjectionMapper =>
         ObjectProjectionMapper != null;
@@ -57,28 +59,20 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     protected AbstractKeyReadOnlyAppService(IReadOnlyRepository<TEntity> repository)
     {
         ReadOnlyRepository = repository;
-
-        ObjectProjectionMapper =
-            LazyServiceProvider.LazyGetService<
-                IQueryProjectionMapper<TEntity, TGetOutputDto>>();
-
-        ListProjectionMapper =
-            LazyServiceProvider.LazyGetService<
-                IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
     }
 
     public virtual async Task<TGetOutputDto> GetAsync(TKey id)
     {
         await CheckGetPolicyAsync();
 
-        if (UseObjectProjectionMapper && ObjectProjectionMapper != null)
+        var projectionMapper = ObjectProjectionMapper;
+
+        if (UseObjectProjectionMapper && projectionMapper != null)
         {
             var query = await GetEntityByIdQueryAsync(id);
 
-            var dto =
-                await AsyncExecuter.FirstOrDefaultAsync(
-                    ObjectProjectionMapper.ProjectTo(query)
-                )
+            var dto = 
+                await AsyncExecuter.FirstOrDefaultAsync(projectionMapper.ProjectTo(query))
                 ?? throw new EntityNotFoundException(typeof(TEntity), id);
 
             return dto;
@@ -103,10 +97,12 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
             query = ApplySorting(query, input);
             query = ApplyPaging(query, input);
 
-            if (UseListProjectionMapper && ListProjectionMapper != null)
+            var projectionMapper = ListProjectionMapper;
+
+            if (UseListProjectionMapper && projectionMapper != null)
             {
                 entityDtos = await AsyncExecuter.ToListAsync(
-                    ListProjectionMapper.ProjectTo(query)
+                    projectionMapper.ProjectTo(query)
                 );
             }
             else
@@ -128,7 +124,7 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         throw new NotImplementedException(
             "Override this method to create the query used for getting an entity by id."
-        );
+            );
     }
 
     protected virtual async Task CheckGetPolicyAsync()

From 331e3f03d5115a175e5b165862efaffc516e0767 Mon Sep 17 00:00:00 2001
From: Mohamed Nazem <109486038+nazem0@users.noreply.github.com>
Date: Wed, 19 Aug 2026 18:40:32 +0300
Subject: [PATCH 07/17] refactor: remove redundant query projection mapper base
 class

---
 .../Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs      | 8 +++++++-
 .../Volo/Abp/ObjectMapping/QueryProjectionMapper.cs       | 8 --------
 2 files changed, 7 insertions(+), 9 deletions(-)
 delete mode 100644 framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs

diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
index 5fe9f955b8..98deb9e4c4 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
@@ -6,4 +6,10 @@ namespace Volo.Abp.ObjectMapping;
 public interface IQueryProjectionMapper<TSource, TDestination> : ITransientDependency
 {
     IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
-}
\ No newline at end of file
+}
+
+//[Mapper(RequiredMappingStrategy = RequiredMappingStrategy.Target)]
+//public partial class GetSectorMapper : IQueryProjectionMapper<Sector, GetSectorsDto>
+//{
+//    public partial IQueryable<GetSectorsDto> ProjectTo(IQueryable<Sector> source);
+//}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
deleted file mode 100644
index 23bfb21141..0000000000
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/QueryProjectionMapper.cs
+++ /dev/null
@@ -1,8 +0,0 @@
-using System.Linq;
-
-namespace Volo.Abp.ObjectMapping;
-
-public abstract class QueryProjectionMapper<TSource, TDestination> : IQueryProjectionMapper<TSource, TDestination>
-{
-    public abstract IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
-}
\ No newline at end of file

From 029cc7de47904925754bc5807f17f3b324ace049 Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 10:27:11 +0800
Subject: [PATCH 08/17] Fix query projection for CrudAppService and register
 projection mappers

* Fall back to GetEntityByIdAsync when a by-id query can not be created
* Expose IQueryProjectionMapper implementations like IObjectMapper does
* Document query projection and cover EF Core, MongoDB and Mapperly
---
 .../application-services.md                   |  51 ++++++++-
 .../Services/AbstractKeyReadOnlyAppService.cs |  61 +++++-----
 .../Application/Services/CrudAppService.cs    |   7 ++
 .../Services/ReadOnlyAppService.cs            |   8 +-
 .../ObjectMapping/AbpObjectMappingModule.cs   |   8 ++
 .../ObjectMapping/IQueryProjectionMapper.cs   |  38 ++++---
 .../Services/QueryProjection/Book.cs          |  23 ++++
 .../BookAbstractKeyAppService.cs              |  27 +++++
 .../QueryProjection/BookAppService.cs         |  13 +++
 .../BookCustomizedAppService.cs               |  28 +++++
 .../Services/QueryProjection/BookDto.cs       |   9 ++
 .../QueryProjection/BookLiteAppService.cs     |  13 +++
 .../Services/QueryProjection/BookLiteDto.cs   |   9 ++
 .../QueryProjection/BookObjectMapper.cs       |  36 ++++++
 .../Services/QueryProjection/BookProjector.cs |  18 +++
 .../QueryProjection/BookReadOnlyAppService.cs |  13 +++
 .../QueryProjection/BookRepository.cs         | 106 ++++++++++++++++++
 .../BookWithoutProjectionAppService.cs        |  18 +++
 .../QueryProjection/QueryProjection_Tests.cs  | 103 +++++++++++++++++
 .../EntityWithIntPkProjectionAppService.cs    |  14 +++
 .../EntityWithIntPkProjectionDto.cs           |   8 ++
 .../Applications/EntityWithIntPkProjector.cs  |  17 +++
 .../PersonProjectionAppService.cs             |  15 +++
 .../Applications/PersonProjectionDto.cs       |   9 ++
 .../Applications/PersonProjector.cs           |  17 +++
 .../Applications/QueryProjection_Tests.cs     |  66 +++++++++++
 .../AbpMapperlyQueryProjection_Tests.cs       |  31 +++++
 .../SampleClasses/MyEntityQueryProjector.cs   |  11 ++
 .../PersonProjectionAppService.cs             |  15 +++
 .../Applications/PersonProjectionDto.cs       |   9 ++
 .../MongoDB/Applications/PersonProjector.cs   |  17 +++
 .../Applications/QueryProjection_Tests.cs     |  46 ++++++++
 32 files changed, 813 insertions(+), 51 deletions(-)
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/Book.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDto.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteDto.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookReadOnlyAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookRepository.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionAppService.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionDto.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionAppService.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionDto.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
 create mode 100644 framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
 create mode 100644 framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
 create mode 100644 framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionAppService.cs
 create mode 100644 framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionDto.cs
 create mode 100644 framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
 create mode 100644 framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/QueryProjection_Tests.cs

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index 8683241534..74ae2adf50 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -1,4 +1,4 @@
-```json
+```json
 //[doc-seo]
 {
     "Description": "Learn how to implement application services in the ABP Framework to expose domain logic and streamline presentation layer interactions."
@@ -444,6 +444,7 @@ These methods are low level methods that can control how to query entities from
 * `ApplyPaging` is used to make paging on the query. If your `TGetListInput` already implements `IPagedResultRequest`, you don't need to override this since the ABP automatically understands it and performs the paging.
 * `ApplySorting` is used to sort (order by...) the query. If your `TGetListInput` already implements the `ISortedResultRequest`, ABP automatically sorts the query. If not, it fallbacks to the `ApplyDefaultSorting` which tries to sort by creation time, if your entity implements the standard `IHasCreationTime` interface.
 * `GetEntityByIdAsync` is used to get an entity by id, which calls `Repository.GetAsync(id)` by default.
+* `GetEntityByIdQueryOrNullAsync` is used to create a query for a single entity by id, which is only needed for the *Query Projection* explained below. It returns `null` if the application service can not create such a query, then `GetEntityByIdAsync` is used.
 * `DeleteByIdAsync` is used to delete an entity by id, which calls `Repository.DeleteAsync(id)` by default.
 
 #### Object to Object Mapping
@@ -456,6 +457,54 @@ These methods are used to convert Entities to DTOs and vice verse. They use the
   * `MapToEntityAsync(TCreateInput)` is used to create an entity from `TCreateInput`.
   * `MapToEntityAsync(TUpdateInput, TEntity)` is used to update an existing entity from `TUpdateInput`.
 
+#### Query Projection
+
+`GetAsync` and `GetListAsync` get the entities from the database, then map them to DTOs in the memory. If your DTO uses only a few properties of a large entity, you can project the query to the DTO instead, so the database returns only the columns you need.
+
+Implement the `IQueryProjectionMapper<TEntity, TDto>` interface to define a projection:
+
+````csharp
+using System.Linq;
+using Volo.Abp.ObjectMapping;
+
+namespace MyProject.Books;
+
+public class BookProjector : IQueryProjectionMapper<Book, BookDto>
+{
+    public IQueryable<BookDto> ProjectTo(IQueryable<Book> source)
+    {
+        return source.Select(book => new BookDto
+        {
+            Id = book.Id,
+            Name = book.Name
+        });
+    }
+}
+````
+
+[Mapperly](https://mapperly.riok.app/) can generate that method for you:
+
+````csharp
+[Mapper]
+public partial class BookProjector : IQueryProjectionMapper<Book, BookDto>
+{
+    public partial IQueryable<BookDto> ProjectTo(IQueryable<Book> source);
+}
+````
+
+ABP registers the projection mappers by convention, you don't need to configure anything else. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
+
+> The projection replaces the entity based extension points. `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync`, `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore. If an application service needs to keep using them, override the `GetProjectionMapper` or `GetListProjectionMapper` property and return `null`:
+
+````csharp
+public class BookAppService : CrudAppService<Book, BookDto, Guid>
+{
+    protected override IQueryProjectionMapper<Book, BookDto>? GetProjectionMapper => null;
+
+    //...
+}
+````
+
 ## Miscellaneous
 
 ### Working with Streams
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
index 0c53ac2705..72f6946930 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
@@ -44,17 +44,19 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected virtual string? GetListPolicyName { get; set; }
 
-    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? ObjectProjectionMapper =>
-        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetOutputDto>>();
-
-    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? ListProjectionMapper =>
-        LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
-
-    protected virtual bool UseObjectProjectionMapper =>
-        ObjectProjectionMapper != null;
+    /// <summary>
+    /// <see cref="GetEntityByIdAsync"/> and <see cref="MapToGetOutputDtoAsync"/> are not used
+    /// while a projection mapper is available. Override and return null to keep using them.
+    /// </summary>
+    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? GetProjectionMapper
+        => LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetOutputDto>>();
 
-    protected virtual bool UseListProjectionMapper =>
-        ListProjectionMapper != null;
+    /// <summary>
+    /// <see cref="MapToGetListOutputDtosAsync"/> is not used while a projection mapper is
+    /// available. Override and return null to keep using it.
+    /// </summary>
+    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? GetListProjectionMapper
+        => LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
 
     protected AbstractKeyReadOnlyAppService(IReadOnlyRepository<TEntity> repository)
     {
@@ -65,17 +67,15 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         await CheckGetPolicyAsync();
 
-        var projectionMapper = ObjectProjectionMapper;
-
-        if (UseObjectProjectionMapper && projectionMapper != null)
+        var projectionMapper = GetProjectionMapper;
+        if (projectionMapper != null)
         {
-            var query = await GetEntityByIdQueryAsync(id);
-
-            var dto = 
-                await AsyncExecuter.FirstOrDefaultAsync(projectionMapper.ProjectTo(query))
-                ?? throw new EntityNotFoundException(typeof(TEntity), id);
-
-            return dto;
+            var query = await GetEntityByIdQueryOrNullAsync(id);
+            if (query != null)
+            {
+                return await AsyncExecuter.FirstOrDefaultAsync(projectionMapper.ProjectTo(query))
+                       ?? throw new EntityNotFoundException<TEntity>(id);
+            }
         }
 
         var entity = await GetEntityByIdAsync(id);
@@ -97,13 +97,10 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
             query = ApplySorting(query, input);
             query = ApplyPaging(query, input);
 
-            var projectionMapper = ListProjectionMapper;
-
-            if (UseListProjectionMapper && projectionMapper != null)
+            var projectionMapper = GetListProjectionMapper;
+            if (projectionMapper != null)
             {
-                entityDtos = await AsyncExecuter.ToListAsync(
-                    projectionMapper.ProjectTo(query)
-                );
+                entityDtos = await AsyncExecuter.ToListAsync(projectionMapper.ProjectTo(query));
             }
             else
             {
@@ -120,11 +117,13 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected abstract Task<TEntity> GetEntityByIdAsync(TKey id);
 
-    protected virtual Task<IQueryable<TEntity>> GetEntityByIdQueryAsync(TKey id)
+    /// <summary>
+    /// Returns null if this application service can not create a query for a single entity.
+    /// <see cref="GetEntityByIdAsync"/> is used in that case.
+    /// </summary>
+    protected virtual Task<IQueryable<TEntity>?> GetEntityByIdQueryOrNullAsync(TKey id)
     {
-        throw new NotImplementedException(
-            "Override this method to create the query used for getting an entity by id."
-            );
+        return Task.FromResult<IQueryable<TEntity>?>(null);
     }
 
     protected virtual async Task CheckGetPolicyAsync()
@@ -269,4 +268,4 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         return ObjectMapper.Map<TEntity, TGetListOutputDto>(entity);
     }
-}
\ No newline at end of file
+}
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
index 672d85a2be..e47514c257 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
@@ -84,6 +84,13 @@ public abstract class CrudAppService<TEntity, TGetOutputDto, TGetListOutputDto,
         return await Repository.GetAsync(id);
     }
 
+    protected override async Task<IQueryable<TEntity>?> GetEntityByIdQueryOrNullAsync(TKey id)
+    {
+        var query = await Repository.GetQueryableAsync();
+
+        return query.Where(EntityHelper.CreateEqualityExpressionForId<TEntity, TKey>(id));
+    }
+
     protected override void MapToEntity(TUpdateInput updateInput, TEntity entity)
     {
         if (updateInput is IEntityDto<TKey> entityDto)
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
index eab432239c..791085f0a4 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
@@ -37,7 +37,7 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
     protected IReadOnlyRepository<TEntity, TKey> Repository { get; }
 
     protected ReadOnlyAppService(IReadOnlyRepository<TEntity, TKey> repository)
-        : base(repository)
+    : base(repository)
     {
         Repository = repository;
     }
@@ -47,11 +47,11 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
         return await Repository.GetAsync(id);
     }
 
-    protected override async Task<IQueryable<TEntity>> GetEntityByIdQueryAsync(TKey id)
+    protected override async Task<IQueryable<TEntity>?> GetEntityByIdQueryOrNullAsync(TKey id)
     {
         var query = await Repository.GetQueryableAsync();
 
-        return query.Where(e =>e.Id != null && e.Id.Equals(id));
+        return query.Where(EntityHelper.CreateEqualityExpressionForId<TEntity, TKey>(id));
     }
 
     protected override IQueryable<TEntity> ApplyDefaultSorting(IQueryable<TEntity> query)
@@ -65,4 +65,4 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
             return query.OrderByDescending(e => e.Id);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
index e572d6e155..92a67bced9 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
@@ -18,6 +18,14 @@ public class AbpObjectMappingModule : AbpModule
                     typeof(IObjectMapper<,>)
                 ).ConvertAll(t => new ServiceIdentifier(t))
             );
+
+            //Register types for IQueryProjectionMapper<TSource, TDestination> if implements
+            onServiceExposingContext.ExposedTypes.AddRange(
+                ReflectionHelper.GetImplementedGenericTypes(
+                    onServiceExposingContext.ImplementationType,
+                    typeof(IQueryProjectionMapper<,>)
+                ).ConvertAll(t => new ServiceIdentifier(t))
+            );
         });
     }
 
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
index 98deb9e4c4..ff41c67a56 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
@@ -1,15 +1,23 @@
-using System.Linq;
-using Volo.Abp.DependencyInjection;
-
-namespace Volo.Abp.ObjectMapping;
-
-public interface IQueryProjectionMapper<TSource, TDestination> : ITransientDependency
-{
-    IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
-}
-
-//[Mapper(RequiredMappingStrategy = RequiredMappingStrategy.Target)]
-//public partial class GetSectorMapper : IQueryProjectionMapper<Sector, GetSectorsDto>
-//{
-//    public partial IQueryable<GetSectorsDto> ProjectTo(IQueryable<Sector> source);
-//}
\ No newline at end of file
+using System.Linq;
+using Volo.Abp.DependencyInjection;
+
+namespace Volo.Abp.ObjectMapping;
+
+/// <summary>
+/// Projects a query of <typeparamref name="TSource"/> objects to a query of
+/// <typeparamref name="TDestination"/> objects.
+/// Implement this interface to let the query provider translate the projection into the data
+/// store's own query language, instead of loading the source objects into the memory.
+/// </summary>
+/// <typeparam name="TSource">Type of the source objects</typeparam>
+/// <typeparam name="TDestination">Type of the destination objects</typeparam>
+public interface IQueryProjectionMapper<TSource, TDestination> : ITransientDependency
+{
+    /// <summary>
+    /// Projects the given query to a query of <typeparamref name="TDestination"/> objects.
+    /// The returned query must be built on top of <paramref name="source"/>, so the query
+    /// provider can still translate it.
+    /// </summary>
+    /// <param name="source">The query to project</param>
+    IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/Book.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/Book.cs
new file mode 100644
index 0000000000..6211160df4
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/Book.cs
@@ -0,0 +1,23 @@
+using System;
+using Volo.Abp.Domain.Entities;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class Book : Entity<Guid>
+{
+    public string Name { get; set; } = default!;
+
+    public int Price { get; set; }
+
+    public Book()
+    {
+
+    }
+
+    public Book(Guid id, string name, int price)
+        : base(id)
+    {
+        Name = name;
+        Price = price;
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyAppService.cs
new file mode 100644
index 0000000000..1110ff841e
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyAppService.cs
@@ -0,0 +1,27 @@
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookAbstractKeyAppService : AbstractKeyReadOnlyAppService<Book, BookDto, Guid>
+{
+    public BookAbstractKeyAppService(IReadOnlyRepository<Book> repository)
+        : base(repository)
+    {
+
+    }
+
+    protected override async Task<Book> GetEntityByIdAsync(Guid id)
+    {
+        var query = await ReadOnlyRepository.GetQueryableAsync();
+
+        return await AsyncExecuter.FirstAsync(query, book => book.Id == id);
+    }
+
+    protected override IQueryable<Book> ApplyDefaultSorting(IQueryable<Book> query)
+    {
+        return query.OrderBy(book => book.Id);
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAppService.cs
new file mode 100644
index 0000000000..c3ae530e7d
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAppService.cs
@@ -0,0 +1,13 @@
+using System;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookAppService : CrudAppService<Book, BookDto, Guid>
+{
+    public BookAppService(IRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs
new file mode 100644
index 0000000000..b4c756d6b2
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs
@@ -0,0 +1,28 @@
+using System;
+using System.Threading.Tasks;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookCustomizedAppService : CrudAppService<Book, BookDto, Guid>
+{
+    public const string Marker = "-customized";
+
+    public BookCustomizedAppService(IRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+
+    protected override async Task<Book> GetEntityByIdAsync(Guid id)
+    {
+        var book = await base.GetEntityByIdAsync(id);
+        book.Name += Marker;
+        return book;
+    }
+
+    protected override Task<BookDto> MapToGetOutputDtoAsync(Book entity)
+    {
+        return Task.FromResult(new BookDto { Id = entity.Id, Name = entity.Name + Marker });
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDto.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDto.cs
new file mode 100644
index 0000000000..08a2117ec2
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDto.cs
@@ -0,0 +1,9 @@
+using System;
+using Volo.Abp.Application.Dtos;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookDto : EntityDto<Guid>
+{
+    public string Name { get; set; } = default!;
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteAppService.cs
new file mode 100644
index 0000000000..c5b28e058b
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteAppService.cs
@@ -0,0 +1,13 @@
+using System;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookLiteAppService : CrudAppService<Book, BookLiteDto, Guid>
+{
+    public BookLiteAppService(IRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteDto.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteDto.cs
new file mode 100644
index 0000000000..7ab0408c85
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookLiteDto.cs
@@ -0,0 +1,9 @@
+using System;
+using Volo.Abp.Application.Dtos;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookLiteDto : EntityDto<Guid>
+{
+    public string Name { get; set; } = default!;
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs
new file mode 100644
index 0000000000..f5668b9c29
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs
@@ -0,0 +1,36 @@
+using Volo.Abp.DependencyInjection;
+using Volo.Abp.ObjectMapping;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookObjectMapper :
+    IObjectMapper<Book, BookDto>,
+    IObjectMapper<Book, BookLiteDto>,
+    ITransientDependency
+{
+    public const string Marker = "-mapped";
+
+    public BookDto Map(Book source)
+    {
+        return new BookDto { Id = source.Id, Name = source.Name + Marker };
+    }
+
+    public BookDto Map(Book source, BookDto destination)
+    {
+        destination.Id = source.Id;
+        destination.Name = source.Name + Marker;
+        return destination;
+    }
+
+    BookLiteDto IObjectMapper<Book, BookLiteDto>.Map(Book source)
+    {
+        return new BookLiteDto { Id = source.Id, Name = source.Name + Marker };
+    }
+
+    BookLiteDto IObjectMapper<Book, BookLiteDto>.Map(Book source, BookLiteDto destination)
+    {
+        destination.Id = source.Id;
+        destination.Name = source.Name + Marker;
+        return destination;
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
new file mode 100644
index 0000000000..89342525ac
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
@@ -0,0 +1,18 @@
+using System.Linq;
+using Volo.Abp.ObjectMapping;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookProjector : IQueryProjectionMapper<Book, BookDto>
+{
+    public const string Marker = "-projected";
+
+    public IQueryable<BookDto> ProjectTo(IQueryable<Book> source)
+    {
+        return source.Select(book => new BookDto
+        {
+            Id = book.Id,
+            Name = book.Name + Marker
+        });
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookReadOnlyAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookReadOnlyAppService.cs
new file mode 100644
index 0000000000..9a80d741fb
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookReadOnlyAppService.cs
@@ -0,0 +1,13 @@
+using System;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookReadOnlyAppService : ReadOnlyAppService<Book, BookDto, Guid>
+{
+    public BookReadOnlyAppService(IReadOnlyRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookRepository.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookRepository.cs
new file mode 100644
index 0000000000..75da4e0da6
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookRepository.cs
@@ -0,0 +1,106 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Threading;
+using System.Threading.Tasks;
+using Volo.Abp.DependencyInjection;
+using Volo.Abp.Domain.Entities;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+[ExposeServices(
+    typeof(IRepository<Book, Guid>),
+    typeof(IReadOnlyRepository<Book, Guid>),
+    typeof(IReadOnlyRepository<Book>))]
+public class BookRepository : RepositoryBase<Book, Guid>, ISingletonDependency
+{
+    private readonly List<Book> _books = new();
+
+    public BookRepository()
+        : base("InMemory")
+    {
+
+    }
+
+    public override Task<IQueryable<Book>> GetQueryableAsync()
+    {
+        return Task.FromResult(_books.AsQueryable());
+    }
+
+    [Obsolete("Use GetQueryableAsync method.")]
+    protected override IQueryable<Book> GetQueryable()
+    {
+        return _books.AsQueryable();
+    }
+
+    public override Task<Book> GetAsync(Guid id, bool includeDetails = true, CancellationToken cancellationToken = default)
+    {
+        var book = _books.FirstOrDefault(x => x.Id == id);
+        if (book == null)
+        {
+            throw new EntityNotFoundException(typeof(Book), id);
+        }
+
+        return Task.FromResult(book);
+    }
+
+    public override Task<Book> FindAsync(Guid id, bool includeDetails = true, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult(_books.FirstOrDefault(x => x.Id == id));
+    }
+
+    public override Task<Book> FindAsync(Expression<Func<Book, bool>> predicate, bool includeDetails = true, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult(_books.AsQueryable().FirstOrDefault(predicate));
+    }
+
+    public override Task<List<Book>> GetListAsync(bool includeDetails = false, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult(_books.ToList());
+    }
+
+    public override Task<List<Book>> GetListAsync(Expression<Func<Book, bool>> predicate, bool includeDetails = false, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult(_books.AsQueryable().Where(predicate).ToList());
+    }
+
+    public override Task<List<Book>> GetPagedListAsync(int skipCount, int maxResultCount, string sorting, bool includeDetails = false, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult(_books.Skip(skipCount).Take(maxResultCount).ToList());
+    }
+
+    public override Task<long> GetCountAsync(CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult((long)_books.Count);
+    }
+
+    public override Task<Book> InsertAsync(Book entity, bool autoSave = false, CancellationToken cancellationToken = default)
+    {
+        _books.Add(entity);
+        return Task.FromResult(entity);
+    }
+
+    public override Task<Book> UpdateAsync(Book entity, bool autoSave = false, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult(entity);
+    }
+
+    public override Task DeleteAsync(Book entity, bool autoSave = false, CancellationToken cancellationToken = default)
+    {
+        _books.Remove(entity);
+        return Task.CompletedTask;
+    }
+
+    public override Task DeleteAsync(Expression<Func<Book, bool>> predicate, bool autoSave = false, CancellationToken cancellationToken = default)
+    {
+        _books.RemoveAll(new Predicate<Book>(predicate.Compile()));
+        return Task.CompletedTask;
+    }
+
+    public override Task DeleteDirectAsync(Expression<Func<Book, bool>> predicate, CancellationToken cancellationToken = default)
+    {
+        return DeleteAsync(predicate);
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
new file mode 100644
index 0000000000..f061781282
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
@@ -0,0 +1,18 @@
+using System;
+using Volo.Abp.Domain.Repositories;
+using Volo.Abp.ObjectMapping;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookWithoutProjectionAppService : CrudAppService<Book, BookDto, Guid>
+{
+    protected override IQueryProjectionMapper<Book, BookDto> GetProjectionMapper => null;
+
+    protected override IQueryProjectionMapper<Book, BookDto> GetListProjectionMapper => null;
+
+    public BookWithoutProjectionAppService(IRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
new file mode 100644
index 0000000000..3f01c930ba
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
@@ -0,0 +1,103 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Shouldly;
+using Volo.Abp.Application.Dtos;
+using Volo.Abp.Domain.Entities;
+using Volo.Abp.Domain.Repositories;
+using Volo.Abp.ObjectMapping;
+using Xunit;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class QueryProjection_Tests : AbpDddApplicationTestBase
+{
+    private readonly Guid _bookId = Guid.NewGuid();
+
+    public QueryProjection_Tests()
+    {
+        var repository = GetRequiredService<IRepository<Book, Guid>>();
+        repository.InsertAsync(new Book(_bookId, "Hitchhiker's Guide", 42)).GetAwaiter().GetResult();
+    }
+
+    [Fact]
+    public void Should_Resolve_Projection_Mapper_Independent_From_The_Class_Name()
+    {
+        ServiceProvider.GetService<IQueryProjectionMapper<Book, BookDto>>()
+            .ShouldBeOfType<BookProjector>();
+    }
+
+    [Fact]
+    public async Task Should_Project_On_The_Query_For_CrudAppService()
+    {
+        var appService = GetRequiredService<BookAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookProjector.Marker);
+        (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
+            .Items[0].Name.ShouldEndWith(BookProjector.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Project_On_The_Query_For_ReadOnlyAppService()
+    {
+        var appService = GetRequiredService<BookReadOnlyAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookProjector.Marker);
+        (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
+            .Items[0].Name.ShouldEndWith(BookProjector.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Throw_EntityNotFoundException_If_The_Projected_Entity_Does_Not_Exist()
+    {
+        var appService = GetRequiredService<BookAppService>();
+
+        await Should.ThrowAsync<EntityNotFoundException>(async () => await appService.GetAsync(Guid.NewGuid()));
+    }
+
+    [Fact]
+    public async Task Should_Use_The_Object_Mapper_If_No_Projection_Mapper_Was_Registered()
+    {
+        var appService = GetRequiredService<BookLiteAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookObjectMapper.Marker);
+        (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
+            .Items[0].Name.ShouldEndWith(BookObjectMapper.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Use_The_Object_Mapper_If_The_Projection_Was_Disabled()
+    {
+        var appService = GetRequiredService<BookWithoutProjectionAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookObjectMapper.Marker);
+        (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
+            .Items[0].Name.ShouldEndWith(BookObjectMapper.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Not_Use_The_Entity_Based_Overrides_While_Projecting()
+    {
+        var appService = GetRequiredService<BookCustomizedAppService>();
+
+        //A projection mapper is registered for <Book, BookDto>, so GetEntityByIdAsync and
+        //MapToGetOutputDtoAsync of this application service are skipped by design.
+        var dto = await appService.GetAsync(_bookId);
+
+        dto.Name.ShouldEndWith(BookProjector.Marker);
+        dto.Name.ShouldNotContain(BookCustomizedAppService.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Use_The_Object_Mapper_If_The_Entity_Query_Can_Not_Be_Created()
+    {
+        var appService = GetRequiredService<BookAbstractKeyAppService>();
+
+        //GetAsync has no query to project, it falls back to GetEntityByIdAsync
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookObjectMapper.Marker);
+
+        //GetListAsync always has a query, so it is still projected
+        (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
+            .Items[0].Name.ShouldEndWith(BookProjector.Marker);
+    }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionAppService.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionAppService.cs
new file mode 100644
index 0000000000..cc6176cddd
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionAppService.cs
@@ -0,0 +1,14 @@
+using Volo.Abp.Application.Services;
+using Volo.Abp.Domain.Repositories;
+using Volo.Abp.TestApp.Domain;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class EntityWithIntPkProjectionAppService : ReadOnlyAppService<EntityWithIntPk, EntityWithIntPkProjectionDto, int>
+{
+    public EntityWithIntPkProjectionAppService(IReadOnlyRepository<EntityWithIntPk, int> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionDto.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionDto.cs
new file mode 100644
index 0000000000..f6bbebe850
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjectionDto.cs
@@ -0,0 +1,8 @@
+using Volo.Abp.Application.Dtos;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class EntityWithIntPkProjectionDto : EntityDto<int>
+{
+    public string Name { get; set; }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
new file mode 100644
index 0000000000..752dbd9bc8
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
@@ -0,0 +1,17 @@
+using System.Linq;
+using Volo.Abp.ObjectMapping;
+using Volo.Abp.TestApp.Domain;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class EntityWithIntPkProjector : IQueryProjectionMapper<EntityWithIntPk, EntityWithIntPkProjectionDto>
+{
+    public IQueryable<EntityWithIntPkProjectionDto> ProjectTo(IQueryable<EntityWithIntPk> source)
+    {
+        return source.Select(entity => new EntityWithIntPkProjectionDto
+        {
+            Id = entity.Id,
+            Name = entity.Name
+        });
+    }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionAppService.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionAppService.cs
new file mode 100644
index 0000000000..fa51e9407f
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionAppService.cs
@@ -0,0 +1,15 @@
+using System;
+using Volo.Abp.Application.Services;
+using Volo.Abp.Domain.Repositories;
+using Volo.Abp.TestApp.Domain;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class PersonProjectionAppService : ReadOnlyAppService<Person, PersonProjectionDto, Guid>
+{
+    public PersonProjectionAppService(IReadOnlyRepository<Person, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionDto.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionDto.cs
new file mode 100644
index 0000000000..57eef129d0
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjectionDto.cs
@@ -0,0 +1,9 @@
+using System;
+using Volo.Abp.Application.Dtos;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class PersonProjectionDto : EntityDto<Guid>
+{
+    public string Name { get; set; }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
new file mode 100644
index 0000000000..bc817e2499
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
@@ -0,0 +1,17 @@
+using System.Linq;
+using Volo.Abp.ObjectMapping;
+using Volo.Abp.TestApp.Domain;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class PersonProjector : IQueryProjectionMapper<Person, PersonProjectionDto>
+{
+    public IQueryable<PersonProjectionDto> ProjectTo(IQueryable<Person> source)
+    {
+        return source.Select(person => new PersonProjectionDto
+        {
+            Id = person.Id,
+            Name = person.Name
+        });
+    }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
new file mode 100644
index 0000000000..832a1502e4
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
@@ -0,0 +1,66 @@
+using System;
+using System.Threading.Tasks;
+using Shouldly;
+using Volo.Abp.Application.Dtos;
+using Volo.Abp.Domain.Entities;
+using Volo.Abp.Domain.Repositories;
+using Volo.Abp.TestApp;
+using Volo.Abp.TestApp.Domain;
+using Xunit;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class QueryProjection_Tests : EntityFrameworkCoreTestBase
+{
+    private readonly PersonProjectionAppService _personProjectionAppService;
+
+    public QueryProjection_Tests()
+    {
+        _personProjectionAppService = GetRequiredService<PersonProjectionAppService>();
+    }
+
+    [Fact]
+    public async Task Should_Get_A_Projected_Entity()
+    {
+        var dto = await _personProjectionAppService.GetAsync(TestDataBuilder.UserDouglasId);
+
+        dto.Id.ShouldBe(TestDataBuilder.UserDouglasId);
+        dto.Name.ShouldBe("Douglas");
+    }
+
+    [Fact]
+    public async Task Should_Throw_EntityNotFoundException_For_A_Missing_Entity()
+    {
+        (await Should.ThrowAsync<EntityNotFoundException<Person>>(
+            async () => await _personProjectionAppService.GetAsync(Guid.NewGuid()))
+        ).EntityType.ShouldBe(typeof(Person));
+    }
+
+    [Fact]
+    public async Task Should_Get_A_Projected_List()
+    {
+        var result = await _personProjectionAppService.GetListAsync(new PagedAndSortedResultRequestDto());
+
+        result.TotalCount.ShouldBeGreaterThan(0);
+        result.Items.Count.ShouldBe((int)result.TotalCount);
+        result.Items.ShouldContain(x => x.Name == "Douglas");
+    }
+
+    [Fact]
+    public async Task Should_Get_A_Projected_Entity_With_A_Non_Guid_Key()
+    {
+        var appService = GetRequiredService<EntityWithIntPkProjectionAppService>();
+        var entity = await WithUnitOfWorkAsync(
+            async () => await GetRequiredService<IRepository<EntityWithIntPk, int>>().FirstAsync());
+
+        (await appService.GetAsync(entity.Id)).Name.ShouldBe(entity.Name);
+    }
+
+    [Fact]
+    public async Task Should_Apply_The_Soft_Delete_Filter_While_Projecting()
+    {
+        var result = await _personProjectionAppService.GetListAsync(new PagedAndSortedResultRequestDto());
+
+        result.Items.ShouldNotContain(x => x.Id == TestDataBuilder.UserJohnDeletedId);
+    }
+}
diff --git a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
new file mode 100644
index 0000000000..a66baaf503
--- /dev/null
+++ b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Extensions.DependencyInjection;
+using Shouldly;
+using Volo.Abp.Mapperly.SampleClasses;
+using Volo.Abp.ObjectMapping;
+using Volo.Abp.Testing;
+using Xunit;
+
+namespace Volo.Abp.Mapperly;
+
+public class AbpMapperlyQueryProjection_Tests : AbpIntegratedTest<MapperlyTestModule>
+{
+    [Fact]
+    public void Should_Project_A_Queryable()
+    {
+        var projectionMapper = ServiceProvider.GetRequiredService<IQueryProjectionMapper<MyEntity, MyEntityDto>>();
+
+        var entities = new List<MyEntity>
+        {
+            new MyEntity { Id = Guid.NewGuid(), Number = 42 }
+        }.AsQueryable();
+
+        var dtos = projectionMapper.ProjectTo(entities).ToList();
+
+        dtos.Count.ShouldBe(1);
+        dtos[0].Id.ShouldBe(entities.First().Id);
+        dtos[0].Number.ShouldBe(42);
+    }
+}
diff --git a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
new file mode 100644
index 0000000000..80d984e11b
--- /dev/null
+++ b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
@@ -0,0 +1,11 @@
+using System.Linq;
+using Riok.Mapperly.Abstractions;
+using Volo.Abp.ObjectMapping;
+
+namespace Volo.Abp.Mapperly.SampleClasses;
+
+[Mapper]
+public partial class MyEntityQueryProjector : IQueryProjectionMapper<MyEntity, MyEntityDto>
+{
+    public partial IQueryable<MyEntityDto> ProjectTo(IQueryable<MyEntity> source);
+}
diff --git a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionAppService.cs b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionAppService.cs
new file mode 100644
index 0000000000..d625b518e8
--- /dev/null
+++ b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionAppService.cs
@@ -0,0 +1,15 @@
+using System;
+using Volo.Abp.Application.Services;
+using Volo.Abp.Domain.Repositories;
+using Volo.Abp.TestApp.Domain;
+
+namespace Volo.Abp.MongoDB.Applications;
+
+public class PersonProjectionAppService : ReadOnlyAppService<Person, PersonProjectionDto, Guid>
+{
+    public PersonProjectionAppService(IReadOnlyRepository<Person, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionDto.cs b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionDto.cs
new file mode 100644
index 0000000000..2a8e716a8c
--- /dev/null
+++ b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjectionDto.cs
@@ -0,0 +1,9 @@
+using System;
+using Volo.Abp.Application.Dtos;
+
+namespace Volo.Abp.MongoDB.Applications;
+
+public class PersonProjectionDto : EntityDto<Guid>
+{
+    public string Name { get; set; }
+}
diff --git a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
new file mode 100644
index 0000000000..9640f9f45f
--- /dev/null
+++ b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
@@ -0,0 +1,17 @@
+using System.Linq;
+using Volo.Abp.ObjectMapping;
+using Volo.Abp.TestApp.Domain;
+
+namespace Volo.Abp.MongoDB.Applications;
+
+public class PersonProjector : IQueryProjectionMapper<Person, PersonProjectionDto>
+{
+    public IQueryable<PersonProjectionDto> ProjectTo(IQueryable<Person> source)
+    {
+        return source.Select(person => new PersonProjectionDto
+        {
+            Id = person.Id,
+            Name = person.Name
+        });
+    }
+}
diff --git a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/QueryProjection_Tests.cs b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/QueryProjection_Tests.cs
new file mode 100644
index 0000000000..a7bf1367a6
--- /dev/null
+++ b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/QueryProjection_Tests.cs
@@ -0,0 +1,46 @@
+using System;
+using System.Threading.Tasks;
+using Shouldly;
+using Volo.Abp.Application.Dtos;
+using Volo.Abp.Domain.Entities;
+using Volo.Abp.TestApp;
+using Volo.Abp.TestApp.Domain;
+using Xunit;
+
+namespace Volo.Abp.MongoDB.Applications;
+
+[Collection(MongoTestCollection.Name)]
+public class QueryProjection_Tests : MongoDbTestBase
+{
+    private readonly PersonProjectionAppService _personProjectionAppService;
+
+    public QueryProjection_Tests()
+    {
+        _personProjectionAppService = GetRequiredService<PersonProjectionAppService>();
+    }
+
+    [Fact]
+    public async Task Should_Get_A_Projected_Entity()
+    {
+        var dto = await _personProjectionAppService.GetAsync(TestDataBuilder.UserDouglasId);
+
+        dto.Id.ShouldBe(TestDataBuilder.UserDouglasId);
+        dto.Name.ShouldBe("Douglas");
+    }
+
+    [Fact]
+    public async Task Should_Throw_EntityNotFoundException_For_A_Missing_Entity()
+    {
+        await Should.ThrowAsync<EntityNotFoundException<Person>>(
+            async () => await _personProjectionAppService.GetAsync(Guid.NewGuid()));
+    }
+
+    [Fact]
+    public async Task Should_Get_A_Projected_List()
+    {
+        var result = await _personProjectionAppService.GetListAsync(new PagedAndSortedResultRequestDto());
+
+        result.TotalCount.ShouldBeGreaterThan(0);
+        result.Items.ShouldContain(x => x.Name == "Douglas");
+    }
+}

From f00d7df56cbb3c516373fa4ae615604888e67b76 Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 10:53:53 +0800
Subject: [PATCH 09/17] Assert the projected SQL and fix the Mapperly sample in
 the docs

* RequiredMappingStrategy.Target avoids an RMG020 warning per unmapped entity property
---
 .../application-services.md                   |  4 +++-
 .../Applications/QueryProjection_Tests.cs     | 22 +++++++++++++++++++
 .../SampleClasses/MyEntityQueryProjector.cs   |  2 +-
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index 74ae2adf50..d1c0186f6d 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -485,13 +485,15 @@ public class BookProjector : IQueryProjectionMapper<Book, BookDto>
 [Mapperly](https://mapperly.riok.app/) can generate that method for you:
 
 ````csharp
-[Mapper]
+[Mapper(RequiredMappingStrategy = RequiredMappingStrategy.Target)]
 public partial class BookProjector : IQueryProjectionMapper<Book, BookDto>
 {
     public partial IQueryable<BookDto> ProjectTo(IQueryable<Book> source);
 }
 ````
 
+> `RequiredMappingStrategy.Target` tells Mapperly to only require the DTO members to be mapped. Without it, it reports a warning for every entity property that the DTO doesn't have.
+
 ABP registers the projection mappers by convention, you don't need to configure anything else. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
 
 > The projection replaces the entity based extension points. `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync`, `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore. If an application service needs to keep using them, override the `GetProjectionMapper` or `GetListProjectionMapper` property and return `null`:
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
index 832a1502e4..c833a2515a 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
@@ -1,9 +1,12 @@
 using System;
+using System.Linq;
 using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
 using Shouldly;
 using Volo.Abp.Application.Dtos;
 using Volo.Abp.Domain.Entities;
 using Volo.Abp.Domain.Repositories;
+using Volo.Abp.ObjectMapping;
 using Volo.Abp.TestApp;
 using Volo.Abp.TestApp.Domain;
 using Xunit;
@@ -63,4 +66,23 @@ public class QueryProjection_Tests : EntityFrameworkCoreTestBase
 
         result.Items.ShouldNotContain(x => x.Id == TestDataBuilder.UserJohnDeletedId);
     }
+
+    [Fact]
+    public async Task Should_Only_Select_The_Projected_Columns()
+    {
+        await WithUnitOfWorkAsync(async () =>
+        {
+            var repository = GetRequiredService<IReadOnlyRepository<Person, Guid>>();
+            var projector = GetRequiredService<IQueryProjectionMapper<Person, PersonProjectionDto>>();
+
+            var sql = projector.ProjectTo(await repository.GetQueryableAsync()).ToQueryString();
+
+            sql.ShouldContain("\"Name\"");
+            sql.ShouldNotContain("\"Birthday\"");
+            sql.ShouldNotContain("\"ExtraProperties\"");
+
+            //the data filters are still a part of the query
+            sql.ShouldContain("Is_Deleted");
+        });
+    }
 }
diff --git a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
index 80d984e11b..da57936cf6 100644
--- a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
+++ b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
@@ -4,7 +4,7 @@ using Volo.Abp.ObjectMapping;
 
 namespace Volo.Abp.Mapperly.SampleClasses;
 
-[Mapper]
+[Mapper(RequiredMappingStrategy = RequiredMappingStrategy.Target)]
 public partial class MyEntityQueryProjector : IQueryProjectionMapper<MyEntity, MyEntityDto>
 {
     public partial IQueryable<MyEntityDto> ProjectTo(IQueryable<MyEntity> source);

From e3127db7e01304daa0dba71e5bc55584f6c63d7f Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 11:05:22 +0800
Subject: [PATCH 10/17] Point to the mapping libraries for the query projection
 sample

---
 .../domain-driven-design/application-services.md     | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index d1c0186f6d..2aab4cf35a 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -482,17 +482,7 @@ public class BookProjector : IQueryProjectionMapper<Book, BookDto>
 }
 ````
 
-[Mapperly](https://mapperly.riok.app/) can generate that method for you:
-
-````csharp
-[Mapper(RequiredMappingStrategy = RequiredMappingStrategy.Target)]
-public partial class BookProjector : IQueryProjectionMapper<Book, BookDto>
-{
-    public partial IQueryable<BookDto> ProjectTo(IQueryable<Book> source);
-}
-````
-
-> `RequiredMappingStrategy.Target` tells Mapperly to only require the DTO members to be mapped. Without it, it reports a warning for every entity property that the DTO doesn't have.
+You don't have to write the `Select` by hand. Both [Mapperly](https://mapperly.riok.app/) and [AutoMapper](https://docs.automapper.org) can project an `IQueryable`, refer to their own documentation for it and to the [object to object mapping document](../../infrastructure/object-to-object-mapping.md) for their ABP integrations.
 
 ABP registers the projection mappers by convention, you don't need to configure anything else. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
 

From d6876b85717f266ee6351233fd8d98cbd8c99e6c Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 11:26:52 +0800
Subject: [PATCH 11/17] Rename the query projection API

* IQueryableMapper pairs with IObjectMapper, CreateEntityQueryAsync with CreateFilteredQueryAsync
---
 .../application-services.md                   | 10 +++---
 .../Services/AbstractKeyReadOnlyAppService.cs | 31 ++++++++++---------
 .../Application/Services/CrudAppService.cs    |  2 +-
 .../Services/ReadOnlyAppService.cs            |  2 +-
 .../ObjectMapping/AbpObjectMappingModule.cs   |  4 +--
 .../ObjectMapping/IQueryProjectionMapper.cs   | 23 --------------
 .../Abp/ObjectMapping/IQueryableMapper.cs     | 21 +++++++++++++
 .../Services/QueryProjection/BookProjector.cs |  2 +-
 .../BookWithoutProjectionAppService.cs        |  4 +--
 .../QueryProjection/QueryProjection_Tests.cs  |  4 +--
 .../Applications/EntityWithIntPkProjector.cs  |  2 +-
 .../Applications/PersonProjector.cs           |  2 +-
 .../Applications/QueryProjection_Tests.cs     |  2 +-
 .../AbpMapperlyQueryProjection_Tests.cs       |  2 +-
 .../SampleClasses/MyEntityQueryProjector.cs   |  2 +-
 .../MongoDB/Applications/PersonProjector.cs   |  2 +-
 16 files changed, 57 insertions(+), 58 deletions(-)
 delete mode 100644 framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
 create mode 100644 framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryableMapper.cs

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index 2aab4cf35a..5c548820aa 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -444,7 +444,7 @@ These methods are low level methods that can control how to query entities from
 * `ApplyPaging` is used to make paging on the query. If your `TGetListInput` already implements `IPagedResultRequest`, you don't need to override this since the ABP automatically understands it and performs the paging.
 * `ApplySorting` is used to sort (order by...) the query. If your `TGetListInput` already implements the `ISortedResultRequest`, ABP automatically sorts the query. If not, it fallbacks to the `ApplyDefaultSorting` which tries to sort by creation time, if your entity implements the standard `IHasCreationTime` interface.
 * `GetEntityByIdAsync` is used to get an entity by id, which calls `Repository.GetAsync(id)` by default.
-* `GetEntityByIdQueryOrNullAsync` is used to create a query for a single entity by id, which is only needed for the *Query Projection* explained below. It returns `null` if the application service can not create such a query, then `GetEntityByIdAsync` is used.
+* `CreateEntityQueryAsync` is used to create a query for a single entity by id, which is only needed for the *Query Projection* explained below. It returns `null` if the application service can not create such a query, then `GetEntityByIdAsync` is used.
 * `DeleteByIdAsync` is used to delete an entity by id, which calls `Repository.DeleteAsync(id)` by default.
 
 #### Object to Object Mapping
@@ -461,7 +461,7 @@ These methods are used to convert Entities to DTOs and vice verse. They use the
 
 `GetAsync` and `GetListAsync` get the entities from the database, then map them to DTOs in the memory. If your DTO uses only a few properties of a large entity, you can project the query to the DTO instead, so the database returns only the columns you need.
 
-Implement the `IQueryProjectionMapper<TEntity, TDto>` interface to define a projection:
+Implement the `IQueryableMapper<TEntity, TDto>` interface to define a projection:
 
 ````csharp
 using System.Linq;
@@ -469,7 +469,7 @@ using Volo.Abp.ObjectMapping;
 
 namespace MyProject.Books;
 
-public class BookProjector : IQueryProjectionMapper<Book, BookDto>
+public class BookProjector : IQueryableMapper<Book, BookDto>
 {
     public IQueryable<BookDto> ProjectTo(IQueryable<Book> source)
     {
@@ -486,12 +486,12 @@ You don't have to write the `Select` by hand. Both [Mapperly](https://mapperly.r
 
 ABP registers the projection mappers by convention, you don't need to configure anything else. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
 
-> The projection replaces the entity based extension points. `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync`, `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore. If an application service needs to keep using them, override the `GetProjectionMapper` or `GetListProjectionMapper` property and return `null`:
+> The projection replaces the entity based extension points. `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync`, `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore. If an application service needs to keep using them, override the `GetQueryableMapper` or `GetListQueryableMapper` property and return `null`:
 
 ````csharp
 public class BookAppService : CrudAppService<Book, BookDto, Guid>
 {
-    protected override IQueryProjectionMapper<Book, BookDto>? GetProjectionMapper => null;
+    protected override IQueryableMapper<Book, BookDto>? GetQueryableMapper => null;
 
     //...
 }
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
index 72f6946930..d2cba1c4e6 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
@@ -45,18 +45,20 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     protected virtual string? GetListPolicyName { get; set; }
 
     /// <summary>
-    /// <see cref="GetEntityByIdAsync"/> and <see cref="MapToGetOutputDtoAsync"/> are not used
-    /// while a projection mapper is available. Override and return null to keep using them.
+    /// Used by the <see cref="GetAsync"/> to project the query to the <typeparamref name="TGetOutputDto"/>.
+    /// It returns the registered mapper or null by default.
+    /// The <see cref="GetEntityByIdAsync"/> and the <see cref="MapToGetOutputDtoAsync"/> are not used when it returns a mapper.
     /// </summary>
-    protected virtual IQueryProjectionMapper<TEntity, TGetOutputDto>? GetProjectionMapper
-        => LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetOutputDto>>();
+    protected virtual IQueryableMapper<TEntity, TGetOutputDto>? GetQueryableMapper
+        => LazyServiceProvider.LazyGetService<IQueryableMapper<TEntity, TGetOutputDto>>();
 
     /// <summary>
-    /// <see cref="MapToGetListOutputDtosAsync"/> is not used while a projection mapper is
-    /// available. Override and return null to keep using it.
+    /// Used by the <see cref="GetListAsync"/> to project the query to the <typeparamref name="TGetListOutputDto"/>.
+    /// It returns the registered mapper or null by default.
+    /// The <see cref="MapToGetListOutputDtosAsync"/> is not used when it returns a mapper.
     /// </summary>
-    protected virtual IQueryProjectionMapper<TEntity, TGetListOutputDto>? GetListProjectionMapper
-        => LazyServiceProvider.LazyGetService<IQueryProjectionMapper<TEntity, TGetListOutputDto>>();
+    protected virtual IQueryableMapper<TEntity, TGetListOutputDto>? GetListQueryableMapper
+        => LazyServiceProvider.LazyGetService<IQueryableMapper<TEntity, TGetListOutputDto>>();
 
     protected AbstractKeyReadOnlyAppService(IReadOnlyRepository<TEntity> repository)
     {
@@ -67,10 +69,10 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         await CheckGetPolicyAsync();
 
-        var projectionMapper = GetProjectionMapper;
+        var projectionMapper = GetQueryableMapper;
         if (projectionMapper != null)
         {
-            var query = await GetEntityByIdQueryOrNullAsync(id);
+            var query = await CreateEntityQueryAsync(id);
             if (query != null)
             {
                 return await AsyncExecuter.FirstOrDefaultAsync(projectionMapper.ProjectTo(query))
@@ -97,7 +99,7 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
             query = ApplySorting(query, input);
             query = ApplyPaging(query, input);
 
-            var projectionMapper = GetListProjectionMapper;
+            var projectionMapper = GetListQueryableMapper;
             if (projectionMapper != null)
             {
                 entityDtos = await AsyncExecuter.ToListAsync(projectionMapper.ProjectTo(query));
@@ -118,10 +120,11 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     protected abstract Task<TEntity> GetEntityByIdAsync(TKey id);
 
     /// <summary>
-    /// Returns null if this application service can not create a query for a single entity.
-    /// <see cref="GetEntityByIdAsync"/> is used in that case.
+    /// Should create a query that selects the entity with the given <paramref name="id"/>.
+    /// It returns null by default, then the <see cref="GetEntityByIdAsync"/> is used instead of the projection.
     /// </summary>
-    protected virtual Task<IQueryable<TEntity>?> GetEntityByIdQueryOrNullAsync(TKey id)
+    /// <param name="id">The id of the entity.</param>
+    protected virtual Task<IQueryable<TEntity>?> CreateEntityQueryAsync(TKey id)
     {
         return Task.FromResult<IQueryable<TEntity>?>(null);
     }
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
index e47514c257..196a4a0e6d 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
@@ -84,7 +84,7 @@ public abstract class CrudAppService<TEntity, TGetOutputDto, TGetListOutputDto,
         return await Repository.GetAsync(id);
     }
 
-    protected override async Task<IQueryable<TEntity>?> GetEntityByIdQueryOrNullAsync(TKey id)
+    protected override async Task<IQueryable<TEntity>?> CreateEntityQueryAsync(TKey id)
     {
         var query = await Repository.GetQueryableAsync();
 
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
index 791085f0a4..efcb456212 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
@@ -47,7 +47,7 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
         return await Repository.GetAsync(id);
     }
 
-    protected override async Task<IQueryable<TEntity>?> GetEntityByIdQueryOrNullAsync(TKey id)
+    protected override async Task<IQueryable<TEntity>?> CreateEntityQueryAsync(TKey id)
     {
         var query = await Repository.GetQueryableAsync();
 
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
index 92a67bced9..f0c412fd48 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
@@ -19,11 +19,11 @@ public class AbpObjectMappingModule : AbpModule
                 ).ConvertAll(t => new ServiceIdentifier(t))
             );
 
-            //Register types for IQueryProjectionMapper<TSource, TDestination> if implements
+            //Register types for IQueryableMapper<TSource, TDestination> if implements
             onServiceExposingContext.ExposedTypes.AddRange(
                 ReflectionHelper.GetImplementedGenericTypes(
                     onServiceExposingContext.ImplementationType,
-                    typeof(IQueryProjectionMapper<,>)
+                    typeof(IQueryableMapper<,>)
                 ).ConvertAll(t => new ServiceIdentifier(t))
             );
         });
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
deleted file mode 100644
index ff41c67a56..0000000000
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjectionMapper.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-using System.Linq;
-using Volo.Abp.DependencyInjection;
-
-namespace Volo.Abp.ObjectMapping;
-
-/// <summary>
-/// Projects a query of <typeparamref name="TSource"/> objects to a query of
-/// <typeparamref name="TDestination"/> objects.
-/// Implement this interface to let the query provider translate the projection into the data
-/// store's own query language, instead of loading the source objects into the memory.
-/// </summary>
-/// <typeparam name="TSource">Type of the source objects</typeparam>
-/// <typeparam name="TDestination">Type of the destination objects</typeparam>
-public interface IQueryProjectionMapper<TSource, TDestination> : ITransientDependency
-{
-    /// <summary>
-    /// Projects the given query to a query of <typeparamref name="TDestination"/> objects.
-    /// The returned query must be built on top of <paramref name="source"/>, so the query
-    /// provider can still translate it.
-    /// </summary>
-    /// <param name="source">The query to project</param>
-    IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
-}
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryableMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryableMapper.cs
new file mode 100644
index 0000000000..38cd45bef7
--- /dev/null
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryableMapper.cs
@@ -0,0 +1,21 @@
+using System.Linq;
+using Volo.Abp.DependencyInjection;
+
+namespace Volo.Abp.ObjectMapping;
+
+/// <summary>
+/// Maps a query to another.
+/// Implement this interface to project a query on the data store side, instead of loading the
+/// source objects into the memory and mapping them one by one.
+/// </summary>
+/// <typeparam name="TSource">Type of the source objects</typeparam>
+/// <typeparam name="TDestination">Type of the destination objects</typeparam>
+public interface IQueryableMapper<TSource, TDestination> : ITransientDependency
+{
+    /// <summary>
+    /// Projects the given query. The returned query must be built on top of it, otherwise the
+    /// query provider can not translate the projection.
+    /// </summary>
+    /// <param name="source">The query to project</param>
+    IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
index 89342525ac..f72dc2ada0 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
@@ -3,7 +3,7 @@ using Volo.Abp.ObjectMapping;
 
 namespace Volo.Abp.Application.Services.QueryProjection;
 
-public class BookProjector : IQueryProjectionMapper<Book, BookDto>
+public class BookProjector : IQueryableMapper<Book, BookDto>
 {
     public const string Marker = "-projected";
 
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
index f061781282..d6837edc6c 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
@@ -6,9 +6,9 @@ namespace Volo.Abp.Application.Services.QueryProjection;
 
 public class BookWithoutProjectionAppService : CrudAppService<Book, BookDto, Guid>
 {
-    protected override IQueryProjectionMapper<Book, BookDto> GetProjectionMapper => null;
+    protected override IQueryableMapper<Book, BookDto> GetQueryableMapper => null;
 
-    protected override IQueryProjectionMapper<Book, BookDto> GetListProjectionMapper => null;
+    protected override IQueryableMapper<Book, BookDto> GetListQueryableMapper => null;
 
     public BookWithoutProjectionAppService(IRepository<Book, Guid> repository)
         : base(repository)
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
index 3f01c930ba..348cad0728 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
@@ -23,7 +23,7 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
     [Fact]
     public void Should_Resolve_Projection_Mapper_Independent_From_The_Class_Name()
     {
-        ServiceProvider.GetService<IQueryProjectionMapper<Book, BookDto>>()
+        ServiceProvider.GetService<IQueryableMapper<Book, BookDto>>()
             .ShouldBeOfType<BookProjector>();
     }
 
@@ -80,8 +80,6 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
     {
         var appService = GetRequiredService<BookCustomizedAppService>();
 
-        //A projection mapper is registered for <Book, BookDto>, so GetEntityByIdAsync and
-        //MapToGetOutputDtoAsync of this application service are skipped by design.
         var dto = await appService.GetAsync(_bookId);
 
         dto.Name.ShouldEndWith(BookProjector.Marker);
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
index 752dbd9bc8..81f19b495d 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
@@ -4,7 +4,7 @@ using Volo.Abp.TestApp.Domain;
 
 namespace Volo.Abp.EntityFrameworkCore.Applications;
 
-public class EntityWithIntPkProjector : IQueryProjectionMapper<EntityWithIntPk, EntityWithIntPkProjectionDto>
+public class EntityWithIntPkProjector : IQueryableMapper<EntityWithIntPk, EntityWithIntPkProjectionDto>
 {
     public IQueryable<EntityWithIntPkProjectionDto> ProjectTo(IQueryable<EntityWithIntPk> source)
     {
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
index bc817e2499..2ede252731 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
@@ -4,7 +4,7 @@ using Volo.Abp.TestApp.Domain;
 
 namespace Volo.Abp.EntityFrameworkCore.Applications;
 
-public class PersonProjector : IQueryProjectionMapper<Person, PersonProjectionDto>
+public class PersonProjector : IQueryableMapper<Person, PersonProjectionDto>
 {
     public IQueryable<PersonProjectionDto> ProjectTo(IQueryable<Person> source)
     {
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
index c833a2515a..bcc96c4730 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
@@ -73,7 +73,7 @@ public class QueryProjection_Tests : EntityFrameworkCoreTestBase
         await WithUnitOfWorkAsync(async () =>
         {
             var repository = GetRequiredService<IReadOnlyRepository<Person, Guid>>();
-            var projector = GetRequiredService<IQueryProjectionMapper<Person, PersonProjectionDto>>();
+            var projector = GetRequiredService<IQueryableMapper<Person, PersonProjectionDto>>();
 
             var sql = projector.ProjectTo(await repository.GetQueryableAsync()).ToQueryString();
 
diff --git a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
index a66baaf503..ca2ac86d3a 100644
--- a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
@@ -15,7 +15,7 @@ public class AbpMapperlyQueryProjection_Tests : AbpIntegratedTest<MapperlyTestMo
     [Fact]
     public void Should_Project_A_Queryable()
     {
-        var projectionMapper = ServiceProvider.GetRequiredService<IQueryProjectionMapper<MyEntity, MyEntityDto>>();
+        var projectionMapper = ServiceProvider.GetRequiredService<IQueryableMapper<MyEntity, MyEntityDto>>();
 
         var entities = new List<MyEntity>
         {
diff --git a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
index da57936cf6..d7ad0fb260 100644
--- a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
+++ b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
@@ -5,7 +5,7 @@ using Volo.Abp.ObjectMapping;
 namespace Volo.Abp.Mapperly.SampleClasses;
 
 [Mapper(RequiredMappingStrategy = RequiredMappingStrategy.Target)]
-public partial class MyEntityQueryProjector : IQueryProjectionMapper<MyEntity, MyEntityDto>
+public partial class MyEntityQueryProjector : IQueryableMapper<MyEntity, MyEntityDto>
 {
     public partial IQueryable<MyEntityDto> ProjectTo(IQueryable<MyEntity> source);
 }
diff --git a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
index 9640f9f45f..341ef77d91 100644
--- a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
+++ b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
@@ -4,7 +4,7 @@ using Volo.Abp.TestApp.Domain;
 
 namespace Volo.Abp.MongoDB.Applications;
 
-public class PersonProjector : IQueryProjectionMapper<Person, PersonProjectionDto>
+public class PersonProjector : IQueryableMapper<Person, PersonProjectionDto>
 {
     public IQueryable<PersonProjectionDto> ProjectTo(IQueryable<Person> source)
     {

From 3da29b2b359aa983923cb5ec214413e88bb5736f Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 15:51:19 +0800
Subject: [PATCH 12/17] Add asynchronous hooks and rename the query projection
 API

* IQueryProjector replaces IQueryableMapper, the hooks can await other queries to join them
* A projection must return one row per entity, the total count and the paging come before it
* Pass the ambient cancellation token and detect the missing entity for value type DTOs
---
 .../Services/AbstractKeyReadOnlyAppService.cs | 87 +++++++++++++-----
 .../Services/ApplicationService.cs            |  3 +
 .../Application/Services/CrudAppService.cs    |  4 +-
 .../Services/ReadOnlyAppService.cs            |  4 +-
 .../ObjectMapping/AbpObjectMappingModule.cs   | 18 ++--
 ...IQueryableMapper.cs => IQueryProjector.cs} |  8 +-
 .../BookAbstractKeyProjectingAppService.cs    | 35 ++++++++
 .../BookAsyncProjectionAppService.cs          | 46 ++++++++++
 .../QueryProjection/BookDetailAppService.cs   | 15 ++++
 .../Services/QueryProjection/BookDetailDto.cs |  9 ++
 .../QueryProjection/BookDetailProjector.cs    | 18 ++++
 .../QueryProjection/BookObjectMapper.cs       | 12 +++
 .../Services/QueryProjection/BookProjector.cs |  2 +-
 .../QueryProjection/BookStructAppService.cs   | 13 +++
 .../Services/QueryProjection/BookStructDto.cs | 10 +++
 .../QueryProjection/BookStructProjector.cs    | 16 ++++
 .../BookWithoutProjectionAppService.cs        |  5 +-
 .../IBookNameSuffixProvider.cs                | 19 ++++
 .../QueryProjection/QueryProjection_Tests.cs  | 86 +++++++++++++++++-
 .../AbpEntityFrameworkCoreTestModule.cs       |  2 +
 .../Applications/EntityWithIntPkProjector.cs  |  2 +-
 .../Applications/PersonProjector.cs           |  2 +-
 .../Applications/PersonWithCityAppService.cs  | 51 +++++++++++
 .../Applications/PersonWithCityDto.cs         | 11 +++
 .../Applications/QueryProjection_Tests.cs     | 90 ++++++++++++++++++-
 .../Applications/SqlCommandCapture.cs         | 40 +++++++++
 .../AbpMapperlyQueryProjection_Tests.cs       | 12 ++-
 .../SampleClasses/MyEntityQueryProjector.cs   |  2 +-
 .../MongoDB/Applications/PersonProjector.cs   |  2 +-
 29 files changed, 573 insertions(+), 51 deletions(-)
 rename framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/{IQueryableMapper.cs => IQueryProjector.cs} (62%)
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyProjectingAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAsyncProjectionAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailDto.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailProjector.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructAppService.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructDto.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructProjector.cs
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/IBookNameSuffixProvider.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityAppService.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs
 create mode 100644 framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/SqlCommandCapture.cs

diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
index d2cba1c4e6..e4980074ba 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
@@ -2,12 +2,14 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Dynamic.Core;
+using System.Threading;
 using System.Threading.Tasks;
 using Volo.Abp.Application.Dtos;
 using Volo.Abp.Auditing;
 using Volo.Abp.Domain.Entities;
 using Volo.Abp.Domain.Repositories;
 using Volo.Abp.ObjectMapping;
+using Volo.Abp.Threading;
 
 namespace Volo.Abp.Application.Services;
 
@@ -45,20 +47,18 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     protected virtual string? GetListPolicyName { get; set; }
 
     /// <summary>
-    /// Used by the <see cref="GetAsync"/> to project the query to the <typeparamref name="TGetOutputDto"/>.
-    /// It returns the registered mapper or null by default.
-    /// The <see cref="GetEntityByIdAsync"/> and the <see cref="MapToGetOutputDtoAsync"/> are not used when it returns a mapper.
+    /// Used by the <see cref="CreateGetOutputDtoQueryOrNullAsync"/> to project the query to the <typeparamref name="TGetOutputDto"/>.
+    /// The <see cref="GetEntityByIdAsync"/> and the <see cref="MapToGetOutputDtoAsync"/> are not used while the query is projected.
     /// </summary>
-    protected virtual IQueryableMapper<TEntity, TGetOutputDto>? GetQueryableMapper
-        => LazyServiceProvider.LazyGetService<IQueryableMapper<TEntity, TGetOutputDto>>();
+    protected virtual IQueryProjector<TEntity, TGetOutputDto>? GetOutputDtoQueryProjector
+        => LazyServiceProvider.LazyGetService<IQueryProjector<TEntity, TGetOutputDto>>();
 
     /// <summary>
-    /// Used by the <see cref="GetListAsync"/> to project the query to the <typeparamref name="TGetListOutputDto"/>.
-    /// It returns the registered mapper or null by default.
-    /// The <see cref="MapToGetListOutputDtosAsync"/> is not used when it returns a mapper.
+    /// Used by the <see cref="CreateGetListOutputDtoQueryOrNullAsync"/> to project the query to the <typeparamref name="TGetListOutputDto"/>.
+    /// The <see cref="MapToGetListOutputDtosAsync"/> is not used while the query is projected.
     /// </summary>
-    protected virtual IQueryableMapper<TEntity, TGetListOutputDto>? GetListQueryableMapper
-        => LazyServiceProvider.LazyGetService<IQueryableMapper<TEntity, TGetListOutputDto>>();
+    protected virtual IQueryProjector<TEntity, TGetListOutputDto>? GetListOutputDtoQueryProjector
+        => LazyServiceProvider.LazyGetService<IQueryProjector<TEntity, TGetListOutputDto>>();
 
     protected AbstractKeyReadOnlyAppService(IReadOnlyRepository<TEntity> repository)
     {
@@ -69,15 +69,17 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
     {
         await CheckGetPolicyAsync();
 
-        var projectionMapper = GetQueryableMapper;
-        if (projectionMapper != null)
+        var dtoQuery = await CreateGetOutputDtoQueryOrNullAsync(id);
+        if (dtoQuery != null)
         {
-            var query = await CreateEntityQueryAsync(id);
-            if (query != null)
+            //TGetOutputDto has no class constraint, so a default value can not be used to detect the missing entity
+            var dtos = await AsyncExecuter.ToListAsync(dtoQuery.Take(1), GetCancellationToken());
+            if (dtos.Count == 0)
             {
-                return await AsyncExecuter.FirstOrDefaultAsync(projectionMapper.ProjectTo(query))
-                       ?? throw new EntityNotFoundException<TEntity>(id);
+                throw new EntityNotFoundException<TEntity>(id);
             }
+
+            return dtos[0];
         }
 
         var entity = await GetEntityByIdAsync(id);
@@ -90,7 +92,7 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
         await CheckGetListPolicyAsync();
 
         var query = await CreateFilteredQueryAsync(input);
-        var totalCount = await AsyncExecuter.CountAsync(query);
+        var totalCount = await AsyncExecuter.CountAsync(query, GetCancellationToken());
 
         var entityDtos = new List<TGetListOutputDto>();
 
@@ -99,14 +101,14 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
             query = ApplySorting(query, input);
             query = ApplyPaging(query, input);
 
-            var projectionMapper = GetListQueryableMapper;
-            if (projectionMapper != null)
+            var dtoQuery = await CreateGetListOutputDtoQueryOrNullAsync(query);
+            if (dtoQuery != null)
             {
-                entityDtos = await AsyncExecuter.ToListAsync(projectionMapper.ProjectTo(query));
+                entityDtos = await AsyncExecuter.ToListAsync(dtoQuery, GetCancellationToken());
             }
             else
             {
-                var entities = await AsyncExecuter.ToListAsync(query);
+                var entities = await AsyncExecuter.ToListAsync(query, GetCancellationToken());
                 entityDtos = await MapToGetListOutputDtosAsync(entities);
             }
         }
@@ -119,16 +121,55 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected abstract Task<TEntity> GetEntityByIdAsync(TKey id);
 
+    protected virtual CancellationToken GetCancellationToken(CancellationToken preferredValue = default)
+    {
+        return CancellationTokenProvider.FallbackToProvider(preferredValue);
+    }
+
     /// <summary>
     /// Should create a query that selects the entity with the given <paramref name="id"/>.
-    /// It returns null by default, then the <see cref="GetEntityByIdAsync"/> is used instead of the projection.
+    /// It returns null by default, then the entity is not projected.
     /// </summary>
     /// <param name="id">The id of the entity.</param>
-    protected virtual Task<IQueryable<TEntity>?> CreateEntityQueryAsync(TKey id)
+    protected virtual Task<IQueryable<TEntity>?> CreateEntityQueryOrNullAsync(TKey id)
     {
         return Task.FromResult<IQueryable<TEntity>?>(null);
     }
 
+    /// <summary>
+    /// Projects the query of the entity with the given <paramref name="id"/> to the <typeparamref name="TGetOutputDto"/>.
+    /// It uses the <see cref="GetOutputDtoQueryProjector"/> and the <see cref="CreateEntityQueryOrNullAsync"/> by default,
+    /// and the <see cref="GetEntityByIdAsync"/> is used when it returns null.
+    /// Override it to await other queries, like the query of another aggregate root to join.
+    /// </summary>
+    /// <param name="id">The id of the entity.</param>
+    protected virtual async Task<IQueryable<TGetOutputDto>?> CreateGetOutputDtoQueryOrNullAsync(TKey id)
+    {
+        var queryProjector = GetOutputDtoQueryProjector;
+        if (queryProjector == null)
+        {
+            return null;
+        }
+
+        var query = await CreateEntityQueryOrNullAsync(id);
+
+        return query == null ? null : queryProjector.ProjectTo(query);
+    }
+
+    /// <summary>
+    /// Projects the given entity query to the <typeparamref name="TGetListOutputDto"/>.
+    /// It uses the <see cref="GetListOutputDtoQueryProjector"/> by default,
+    /// and the <see cref="MapToGetListOutputDtosAsync"/> is used when it returns null.
+    /// Override it to await other queries, like the query of another aggregate root to join.
+    /// The projection must return one row per entity: the total count is already calculated and the paging is
+    /// already applied, so adding or removing rows makes the page inconsistent with the total count.
+    /// </summary>
+    /// <param name="query">The sorted and paged entity query.</param>
+    protected virtual Task<IQueryable<TGetListOutputDto>?> CreateGetListOutputDtoQueryOrNullAsync(IQueryable<TEntity> query)
+    {
+        return Task.FromResult(GetListOutputDtoQueryProjector?.ProjectTo(query));
+    }
+
     protected virtual async Task CheckGetPolicyAsync()
     {
         await CheckPolicyAsync(GetPolicyName);
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs
index 4eb285df04..01e9e81354 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs
@@ -19,6 +19,7 @@ using Volo.Abp.Localization;
 using Volo.Abp.MultiTenancy;
 using Volo.Abp.ObjectMapping;
 using Volo.Abp.Settings;
+using Volo.Abp.Threading;
 using Volo.Abp.Timing;
 using Volo.Abp.Uow;
 using Volo.Abp.Users;
@@ -48,6 +49,8 @@ public abstract class ApplicationService :
 
     protected IAsyncQueryableExecuter AsyncExecuter => LazyServiceProvider.LazyGetRequiredService<IAsyncQueryableExecuter>();
 
+    protected ICancellationTokenProvider CancellationTokenProvider => LazyServiceProvider.LazyGetService<ICancellationTokenProvider>(NullCancellationTokenProvider.Instance);
+
     protected Type? ObjectMapperContext { get; set; }
     protected IObjectMapper ObjectMapper => LazyServiceProvider.LazyGetService<IObjectMapper>(provider =>
         ObjectMapperContext == null
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
index 196a4a0e6d..906b138fba 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs
@@ -84,11 +84,11 @@ public abstract class CrudAppService<TEntity, TGetOutputDto, TGetListOutputDto,
         return await Repository.GetAsync(id);
     }
 
-    protected override async Task<IQueryable<TEntity>?> CreateEntityQueryAsync(TKey id)
+    protected override async Task<IQueryable<TEntity>?> CreateEntityQueryOrNullAsync(TKey id)
     {
         var query = await Repository.GetQueryableAsync();
 
-        return query.Where(EntityHelper.CreateEqualityExpressionForId<TEntity, TKey>(id));
+        return query.Where(e => e.Id!.Equals(id));
     }
 
     protected override void MapToEntity(TUpdateInput updateInput, TEntity entity)
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
index efcb456212..c36d17ffc8 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs
@@ -47,11 +47,11 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
         return await Repository.GetAsync(id);
     }
 
-    protected override async Task<IQueryable<TEntity>?> CreateEntityQueryAsync(TKey id)
+    protected override async Task<IQueryable<TEntity>?> CreateEntityQueryOrNullAsync(TKey id)
     {
         var query = await Repository.GetQueryableAsync();
 
-        return query.Where(EntityHelper.CreateEqualityExpressionForId<TEntity, TKey>(id));
+        return query.Where(e => e.Id!.Equals(id));
     }
 
     protected override IQueryable<TEntity> ApplyDefaultSorting(IQueryable<TEntity> query)
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
index f0c412fd48..87e0c43b56 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
@@ -1,4 +1,5 @@
-using Microsoft.Extensions.DependencyInjection;
+using System.Collections.Generic;
+using Microsoft.Extensions.DependencyInjection;
 using Volo.Abp.DependencyInjection;
 using Volo.Abp.Modularity;
 using Volo.Abp.Reflection;
@@ -19,13 +20,14 @@ public class AbpObjectMappingModule : AbpModule
                 ).ConvertAll(t => new ServiceIdentifier(t))
             );
 
-            //Register types for IQueryableMapper<TSource, TDestination> if implements
-            onServiceExposingContext.ExposedTypes.AddRange(
-                ReflectionHelper.GetImplementedGenericTypes(
-                    onServiceExposingContext.ImplementationType,
-                    typeof(IQueryableMapper<,>)
-                ).ConvertAll(t => new ServiceIdentifier(t))
-            );
+            //Register types for IQueryProjector<TSource, TDestination> if implements
+            //The class name convention may have already exposed them, so they are not added twice
+            foreach (var serviceType in ReflectionHelper.GetImplementedGenericTypes(
+                         onServiceExposingContext.ImplementationType,
+                         typeof(IQueryProjector<,>)))
+            {
+                onServiceExposingContext.ExposedTypes.AddIfNotContains(new ServiceIdentifier(serviceType));
+            }
         });
     }
 
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryableMapper.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjector.cs
similarity index 62%
rename from framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryableMapper.cs
rename to framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjector.cs
index 38cd45bef7..1abf5667e6 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryableMapper.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjector.cs
@@ -7,14 +7,16 @@ namespace Volo.Abp.ObjectMapping;
 /// Maps a query to another.
 /// Implement this interface to project a query on the data store side, instead of loading the
 /// source objects into the memory and mapping them one by one.
+/// Implement it once for a source and destination pair, the last registered one is used otherwise.
 /// </summary>
 /// <typeparam name="TSource">Type of the source objects</typeparam>
 /// <typeparam name="TDestination">Type of the destination objects</typeparam>
-public interface IQueryableMapper<TSource, TDestination> : ITransientDependency
+public interface IQueryProjector<TSource, TDestination> : ITransientDependency
 {
     /// <summary>
-    /// Projects the given query. The returned query must be built on top of it, otherwise the
-    /// query provider can not translate the projection.
+    /// Projects the given query. The returned query must be built on top of it and must keep its order,
+    /// with a single destination object for each source object, using expressions the query provider can
+    /// translate. The caller may have already sorted, paged or counted the source query.
     /// </summary>
     /// <param name="source">The query to project</param>
     IQueryable<TDestination> ProjectTo(IQueryable<TSource> source);
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyProjectingAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyProjectingAppService.cs
new file mode 100644
index 0000000000..c6bcf8dbce
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAbstractKeyProjectingAppService.cs
@@ -0,0 +1,35 @@
+#nullable enable
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookAbstractKeyProjectingAppService : AbstractKeyReadOnlyAppService<Book, BookDto, Guid>
+{
+    public BookAbstractKeyProjectingAppService(IReadOnlyRepository<Book> repository)
+        : base(repository)
+    {
+
+    }
+
+    protected override async Task<Book> GetEntityByIdAsync(Guid id)
+    {
+        var query = await ReadOnlyRepository.GetQueryableAsync();
+
+        return await AsyncExecuter.FirstAsync(query, book => book.Id == id);
+    }
+
+    protected override async Task<IQueryable<Book>?> CreateEntityQueryOrNullAsync(Guid id)
+    {
+        var query = await ReadOnlyRepository.GetQueryableAsync();
+
+        return query.Where(book => book.Id == id);
+    }
+
+    protected override IQueryable<Book> ApplyDefaultSorting(IQueryable<Book> query)
+    {
+        return query.OrderBy(book => book.Id);
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAsyncProjectionAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAsyncProjectionAppService.cs
new file mode 100644
index 0000000000..21f7516116
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookAsyncProjectionAppService.cs
@@ -0,0 +1,46 @@
+#nullable enable
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using Volo.Abp.Application.Dtos;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookAsyncProjectionAppService : CrudAppService<Book, BookDto, Guid>
+{
+    public const string Marker = "-async";
+
+    private readonly IBookNameSuffixProvider _suffixProvider;
+
+    public BookAsyncProjectionAppService(
+        IRepository<Book, Guid> repository,
+        IBookNameSuffixProvider suffixProvider)
+        : base(repository)
+    {
+        _suffixProvider = suffixProvider;
+    }
+
+    protected override async Task<IQueryable<BookDto>?> CreateGetOutputDtoQueryOrNullAsync(Guid id)
+    {
+        var query = await Repository.GetQueryableAsync();
+
+        return await ProjectAsync(query.Where(book => book.Id == id));
+    }
+
+    protected override async Task<IQueryable<BookDto>?> CreateGetListOutputDtoQueryOrNullAsync(IQueryable<Book> query)
+    {
+        return await ProjectAsync(query);
+    }
+
+    private async Task<IQueryable<BookDto>> ProjectAsync(IQueryable<Book> query)
+    {
+        var suffix = await _suffixProvider.GetAsync();
+
+        return query.Select(book => new BookDto
+        {
+            Id = book.Id,
+            Name = book.Name + suffix
+        });
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailAppService.cs
new file mode 100644
index 0000000000..ec2139a118
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailAppService.cs
@@ -0,0 +1,15 @@
+using System;
+using Volo.Abp.Application.Dtos;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookDetailAppService :
+    ReadOnlyAppService<Book, BookDetailDto, BookDto, Guid, PagedAndSortedResultRequestDto>
+{
+    public BookDetailAppService(IReadOnlyRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailDto.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailDto.cs
new file mode 100644
index 0000000000..f278d6d721
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailDto.cs
@@ -0,0 +1,9 @@
+using System;
+using Volo.Abp.Application.Dtos;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookDetailDto : EntityDto<Guid>
+{
+    public string Name { get; set; } = default!;
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailProjector.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailProjector.cs
new file mode 100644
index 0000000000..d7e3e19966
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookDetailProjector.cs
@@ -0,0 +1,18 @@
+using System.Linq;
+using Volo.Abp.ObjectMapping;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookDetailProjector : IQueryProjector<Book, BookDetailDto>
+{
+    public const string Marker = "-detail";
+
+    public IQueryable<BookDetailDto> ProjectTo(IQueryable<Book> source)
+    {
+        return source.Select(book => new BookDetailDto
+        {
+            Id = book.Id,
+            Name = book.Name + Marker
+        });
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs
index f5668b9c29..c398f9e25f 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookObjectMapper.cs
@@ -6,6 +6,7 @@ namespace Volo.Abp.Application.Services.QueryProjection;
 public class BookObjectMapper :
     IObjectMapper<Book, BookDto>,
     IObjectMapper<Book, BookLiteDto>,
+    IObjectMapper<BookDto, Book>,
     ITransientDependency
 {
     public const string Marker = "-mapped";
@@ -33,4 +34,15 @@ public class BookObjectMapper :
         destination.Name = source.Name + Marker;
         return destination;
     }
+
+    Book IObjectMapper<BookDto, Book>.Map(BookDto source)
+    {
+        return new Book(source.Id, source.Name, 0);
+    }
+
+    Book IObjectMapper<BookDto, Book>.Map(BookDto source, Book destination)
+    {
+        destination.Name = source.Name;
+        return destination;
+    }
 }
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
index f72dc2ada0..fa292161fc 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookProjector.cs
@@ -3,7 +3,7 @@ using Volo.Abp.ObjectMapping;
 
 namespace Volo.Abp.Application.Services.QueryProjection;
 
-public class BookProjector : IQueryableMapper<Book, BookDto>
+public class BookProjector : IQueryProjector<Book, BookDto>
 {
     public const string Marker = "-projected";
 
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructAppService.cs
new file mode 100644
index 0000000000..34b4945b85
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructAppService.cs
@@ -0,0 +1,13 @@
+using System;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookStructAppService : ReadOnlyAppService<Book, BookStructDto, Guid>
+{
+    public BookStructAppService(IReadOnlyRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructDto.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructDto.cs
new file mode 100644
index 0000000000..f2690bb139
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructDto.cs
@@ -0,0 +1,10 @@
+using System;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public struct BookStructDto
+{
+    public Guid Id { get; set; }
+
+    public string Name { get; set; }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructProjector.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructProjector.cs
new file mode 100644
index 0000000000..4ae26a4b11
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookStructProjector.cs
@@ -0,0 +1,16 @@
+using System.Linq;
+using Volo.Abp.ObjectMapping;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookStructProjector : IQueryProjector<Book, BookStructDto>
+{
+    public IQueryable<BookStructDto> ProjectTo(IQueryable<Book> source)
+    {
+        return source.Select(book => new BookStructDto
+        {
+            Id = book.Id,
+            Name = book.Name
+        });
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
index d6837edc6c..9ad4680d45 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using Volo.Abp.Domain.Repositories;
 using Volo.Abp.ObjectMapping;
@@ -6,9 +7,9 @@ namespace Volo.Abp.Application.Services.QueryProjection;
 
 public class BookWithoutProjectionAppService : CrudAppService<Book, BookDto, Guid>
 {
-    protected override IQueryableMapper<Book, BookDto> GetQueryableMapper => null;
+    protected override IQueryProjector<Book, BookDto>? GetOutputDtoQueryProjector => null;
 
-    protected override IQueryableMapper<Book, BookDto> GetListQueryableMapper => null;
+    protected override IQueryProjector<Book, BookDto>? GetListOutputDtoQueryProjector => null;
 
     public BookWithoutProjectionAppService(IRepository<Book, Guid> repository)
         : base(repository)
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/IBookNameSuffixProvider.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/IBookNameSuffixProvider.cs
new file mode 100644
index 0000000000..747a93c15d
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/IBookNameSuffixProvider.cs
@@ -0,0 +1,19 @@
+using System.Threading.Tasks;
+using Volo.Abp.DependencyInjection;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public interface IBookNameSuffixProvider
+{
+    Task<string> GetAsync();
+}
+
+public class BookNameSuffixProvider : IBookNameSuffixProvider, ITransientDependency
+{
+    public async Task<string> GetAsync()
+    {
+        await Task.Yield();
+
+        return BookAsyncProjectionAppService.Marker;
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
index 348cad0728..228e4591c3 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
@@ -21,9 +21,9 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
     }
 
     [Fact]
-    public void Should_Resolve_Projection_Mapper_Independent_From_The_Class_Name()
+    public void Should_Resolve_The_Projector_Independent_From_The_Class_Name()
     {
-        ServiceProvider.GetService<IQueryableMapper<Book, BookDto>>()
+        ServiceProvider.GetService<IQueryProjector<Book, BookDto>>()
             .ShouldBeOfType<BookProjector>();
     }
 
@@ -56,7 +56,7 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
     }
 
     [Fact]
-    public async Task Should_Use_The_Object_Mapper_If_No_Projection_Mapper_Was_Registered()
+    public async Task Should_Use_The_Object_Mapper_If_No_Projector_Was_Registered()
     {
         var appService = GetRequiredService<BookLiteAppService>();
 
@@ -98,4 +98,84 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
         (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
             .Items[0].Name.ShouldEndWith(BookProjector.Marker);
     }
+
+    [Fact]
+    public async Task Should_Use_The_Asynchronously_Created_Projection_Query()
+    {
+        var appService = GetRequiredService<BookAsyncProjectionAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookAsyncProjectionAppService.Marker);
+        (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
+            .Items[0].Name.ShouldEndWith(BookAsyncProjectionAppService.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Throw_EntityNotFoundException_From_An_Overridden_Projection_Query()
+    {
+        var appService = GetRequiredService<BookAsyncProjectionAppService>();
+
+        await Should.ThrowAsync<EntityNotFoundException>(async () => await appService.GetAsync(Guid.NewGuid()));
+    }
+
+    [Fact]
+    public async Task Should_Throw_EntityNotFoundException_For_A_Value_Type_Dto()
+    {
+        var appService = GetRequiredService<BookStructAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldBe("Hitchhiker's Guide");
+
+        await Should.ThrowAsync<EntityNotFoundException>(async () => await appService.GetAsync(Guid.NewGuid()));
+    }
+
+    [Fact]
+    public async Task Should_Not_Project_On_The_Create_And_Update_Paths()
+    {
+        var appService = GetRequiredService<BookAppService>();
+
+        var created = await appService.CreateAsync(new BookDto { Name = "New Book" });
+        created.Name.ShouldEndWith(BookObjectMapper.Marker);
+
+        var updated = await appService.UpdateAsync(created.Id, new BookDto { Name = "Updated Book" });
+        updated.Name.ShouldEndWith(BookObjectMapper.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Use_A_Different_Projector_For_The_Get_And_The_List()
+    {
+        var appService = GetRequiredService<BookDetailAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookDetailProjector.Marker);
+        (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
+            .Items[0].Name.ShouldEndWith(BookProjector.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Apply_Paging_And_Sorting_Before_Projecting()
+    {
+        var repository = GetRequiredService<IRepository<Book, Guid>>();
+        await repository.InsertAsync(new Book(Guid.NewGuid(), "A Book", 1));
+        await repository.InsertAsync(new Book(Guid.NewGuid(), "Z Book", 2));
+
+        var appService = GetRequiredService<BookAppService>();
+
+        var firstPage = await appService.GetListAsync(
+            new PagedAndSortedResultRequestDto { MaxResultCount = 1, Sorting = "Name" });
+
+        firstPage.TotalCount.ShouldBe(3);
+        firstPage.Items.Count.ShouldBe(1);
+        firstPage.Items[0].Name.ShouldBe("A Book" + BookProjector.Marker);
+
+        var secondPage = await appService.GetListAsync(
+            new PagedAndSortedResultRequestDto { MaxResultCount = 1, SkipCount = 1, Sorting = "Name" });
+
+        secondPage.Items[0].Name.ShouldBe("Hitchhiker's Guide" + BookProjector.Marker);
+    }
+
+    [Fact]
+    public async Task Should_Project_A_Single_Entity_From_An_AbstractKey_Application_Service()
+    {
+        var appService = GetRequiredService<BookAbstractKeyProjectingAppService>();
+
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookProjector.Marker);
+    }
 }
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/AbpEntityFrameworkCoreTestModule.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/AbpEntityFrameworkCoreTestModule.cs
index 27992ed124..fae245bc3a 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/AbpEntityFrameworkCoreTestModule.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/AbpEntityFrameworkCoreTestModule.cs
@@ -7,6 +7,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Volo.Abp.Autofac;
 using Volo.Abp.Data;
 using Volo.Abp.Domain.Repositories;
+using Volo.Abp.EntityFrameworkCore.Applications;
 using Volo.Abp.EntityFrameworkCore.Domain;
 using Volo.Abp.EntityFrameworkCore.Sqlite;
 using Volo.Abp.EntityFrameworkCore.TestApp.FifthContext;
@@ -92,6 +93,7 @@ public class AbpEntityFrameworkCoreTestModule : AbpModule
             options.Configure(abpDbContextConfigurationContext =>
             {
                 abpDbContextConfigurationContext.UseSqlite().AddAbpDbContextOptionsExtension();
+                abpDbContextConfigurationContext.DbContextOptions.AddInterceptors(new SqlCommandCapture());
             });
         });
     }
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
index 81f19b495d..5e97ceca51 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/EntityWithIntPkProjector.cs
@@ -4,7 +4,7 @@ using Volo.Abp.TestApp.Domain;
 
 namespace Volo.Abp.EntityFrameworkCore.Applications;
 
-public class EntityWithIntPkProjector : IQueryableMapper<EntityWithIntPk, EntityWithIntPkProjectionDto>
+public class EntityWithIntPkProjector : IQueryProjector<EntityWithIntPk, EntityWithIntPkProjectionDto>
 {
     public IQueryable<EntityWithIntPkProjectionDto> ProjectTo(IQueryable<EntityWithIntPk> source)
     {
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
index 2ede252731..d9abce7cd8 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonProjector.cs
@@ -4,7 +4,7 @@ using Volo.Abp.TestApp.Domain;
 
 namespace Volo.Abp.EntityFrameworkCore.Applications;
 
-public class PersonProjector : IQueryableMapper<Person, PersonProjectionDto>
+public class PersonProjector : IQueryProjector<Person, PersonProjectionDto>
 {
     public IQueryable<PersonProjectionDto> ProjectTo(IQueryable<Person> source)
     {
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityAppService.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityAppService.cs
new file mode 100644
index 0000000000..f8a8ba01e5
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityAppService.cs
@@ -0,0 +1,51 @@
+#nullable enable
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using Volo.Abp.Application.Services;
+using Volo.Abp.Domain.Repositories;
+using Volo.Abp.TestApp.Domain;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+//City is another aggregate root, so Person has no City navigation property to project.
+public class PersonWithCityAppService : ReadOnlyAppService<Person, PersonWithCityDto, Guid>
+{
+    private readonly IReadOnlyRepository<City, Guid> _cityRepository;
+
+    public PersonWithCityAppService(
+        IReadOnlyRepository<Person, Guid> repository,
+        IReadOnlyRepository<City, Guid> cityRepository)
+        : base(repository)
+    {
+        _cityRepository = cityRepository;
+    }
+
+    protected override async Task<IQueryable<PersonWithCityDto>?> CreateGetOutputDtoQueryOrNullAsync(Guid id)
+    {
+        var people = await CreateEntityQueryOrNullAsync(id);
+
+        return people == null ? null : await JoinCitiesAsync(people);
+    }
+
+    protected override async Task<IQueryable<PersonWithCityDto>?> CreateGetListOutputDtoQueryOrNullAsync(IQueryable<Person> query)
+    {
+        return await JoinCitiesAsync(query);
+    }
+
+    //left join, an inner join would drop the people without a city and break the total count
+    private async Task<IQueryable<PersonWithCityDto>> JoinCitiesAsync(IQueryable<Person> people)
+    {
+        var cities = await _cityRepository.GetQueryableAsync();
+
+        return from person in people
+               join city in cities on person.CityId equals city.Id into personCities
+               from personCity in personCities.DefaultIfEmpty()
+               select new PersonWithCityDto
+               {
+                   Id = person.Id,
+                   Name = person.Name,
+                   CityName = personCity != null ? personCity.Name : null
+               };
+    }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs
new file mode 100644
index 0000000000..db62825b8e
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs
@@ -0,0 +1,11 @@
+using System;
+using Volo.Abp.Application.Dtos;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class PersonWithCityDto : EntityDto<Guid>
+{
+    public string Name { get; set; }
+
+    public string CityName { get; set; }
+}
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
index bcc96c4730..e2d2f45d7c 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
@@ -1,5 +1,7 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.EntityFrameworkCore;
 using Shouldly;
@@ -8,6 +10,8 @@ using Volo.Abp.Domain.Entities;
 using Volo.Abp.Domain.Repositories;
 using Volo.Abp.ObjectMapping;
 using Volo.Abp.TestApp;
+using Volo.Abp.TestApp.Application;
+using Volo.Abp.Threading;
 using Volo.Abp.TestApp.Domain;
 using Xunit;
 
@@ -73,7 +77,7 @@ public class QueryProjection_Tests : EntityFrameworkCoreTestBase
         await WithUnitOfWorkAsync(async () =>
         {
             var repository = GetRequiredService<IReadOnlyRepository<Person, Guid>>();
-            var projector = GetRequiredService<IQueryableMapper<Person, PersonProjectionDto>>();
+            var projector = GetRequiredService<IQueryProjector<Person, PersonProjectionDto>>();
 
             var sql = projector.ProjectTo(await repository.GetQueryableAsync()).ToQueryString();
 
@@ -85,4 +89,88 @@ public class QueryProjection_Tests : EntityFrameworkCoreTestBase
             sql.ShouldContain("Is_Deleted");
         });
     }
+
+    [Fact]
+    public async Task Should_Join_Another_Aggregate_While_Projecting()
+    {
+        var appService = GetRequiredService<PersonWithCityAppService>();
+
+        var dto = await appService.GetAsync(TestDataBuilder.UserDouglasId);
+        dto.CityName.ShouldBe("London");
+
+        var result = await appService.GetListAsync(new PagedAndSortedResultRequestDto());
+        result.Items.ShouldContain(x => x.CityName == "London");
+    }
+
+    [Fact]
+    public async Task Should_Keep_The_Total_Count_While_Joining_Another_Aggregate()
+    {
+        await WithUnitOfWorkAsync(async () =>
+        {
+            await GetRequiredService<IRepository<Person, Guid>>()
+                .InsertAsync(new Person(Guid.NewGuid(), "PersonWithoutCity", 30), autoSave: true);
+        });
+
+        var result = await GetRequiredService<PersonWithCityAppService>()
+            .GetListAsync(new PagedAndSortedResultRequestDto());
+
+        result.Items.Count.ShouldBe((int)result.TotalCount);
+        result.Items.ShouldContain(x => x.Name == "PersonWithoutCity" && x.CityName == null);
+    }
+
+    [Fact]
+    public async Task Should_Execute_The_Projected_Query_From_The_Application_Service()
+    {
+        System.Collections.Concurrent.ConcurrentQueue<string> commands;
+        using (SqlCommandCapture.Begin(out commands))
+        {
+            await GetRequiredService<PersonProjectionAppService>()
+                .GetListAsync(new PagedAndSortedResultRequestDto());
+        }
+
+        //the application service must run the projection itself, not materialize the entities first
+        var select = commands.Last(x => x.Contains("FROM \"People\"") && !x.Contains("COUNT"));
+
+        select.ShouldContain("\"Name\"");
+        select.ShouldNotContain("\"Birthday\"");
+        select.ShouldNotContain("\"ExtraProperties\"");
+    }
+
+    [Fact]
+    public async Task Should_Apply_The_Multi_Tenancy_Filter_While_Projecting()
+    {
+        var result = await GetRequiredService<PersonProjectionAppService>()
+            .GetListAsync(new PagedAndSortedResultRequestDto());
+
+        result.Items.ShouldNotContain(x => x.Name.StartsWith(TestDataBuilder.TenantId1.ToString()));
+    }
+
+    [Fact]
+    public async Task Should_Use_The_Ambient_Cancellation_Token_While_Projecting()
+    {
+        var cancellationTokenProvider = GetRequiredService<ICancellationTokenProvider>();
+        var appService = GetRequiredService<PersonProjectionAppService>();
+
+        using (cancellationTokenProvider.Use(new CancellationToken(canceled: true)))
+        {
+            await Should.ThrowAsync<OperationCanceledException>(async () =>
+                await appService.GetAsync(TestDataBuilder.UserDouglasId));
+
+            await Should.ThrowAsync<OperationCanceledException>(async () =>
+                await appService.GetListAsync(new PagedAndSortedResultRequestDto()));
+        }
+    }
+
+    [Fact]
+    public async Task Should_Use_The_Ambient_Cancellation_Token_Without_A_Projector()
+    {
+        var cancellationTokenProvider = GetRequiredService<ICancellationTokenProvider>();
+        var appService = GetRequiredService<IPeopleAppService>();
+
+        using (cancellationTokenProvider.Use(new CancellationToken(canceled: true)))
+        {
+            await Should.ThrowAsync<OperationCanceledException>(async () =>
+                await appService.GetListAsync(new PagedAndSortedResultRequestDto()));
+        }
+    }
 }
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/SqlCommandCapture.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/SqlCommandCapture.cs
new file mode 100644
index 0000000000..7f70e562e5
--- /dev/null
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/SqlCommandCapture.cs
@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Data.Common;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+
+namespace Volo.Abp.EntityFrameworkCore.Applications;
+
+public class SqlCommandCapture : DbCommandInterceptor
+{
+    private static readonly AsyncLocal<ConcurrentQueue<string>> Commands = new();
+
+    public static IDisposable Begin(out ConcurrentQueue<string> commands)
+    {
+        commands = new ConcurrentQueue<string>();
+        Commands.Value = commands;
+        return new DisposeAction(() => Commands.Value = null);
+    }
+
+    public override InterceptionResult<DbDataReader> ReaderExecuting(
+        DbCommand command,
+        CommandEventData eventData,
+        InterceptionResult<DbDataReader> result)
+    {
+        Commands.Value?.Enqueue(command.CommandText);
+        return base.ReaderExecuting(command, eventData, result);
+    }
+
+    public override ValueTask<InterceptionResult<DbDataReader>> ReaderExecutingAsync(
+        DbCommand command,
+        CommandEventData eventData,
+        InterceptionResult<DbDataReader> result,
+        CancellationToken cancellationToken = default)
+    {
+        Commands.Value?.Enqueue(command.CommandText);
+        return base.ReaderExecutingAsync(command, eventData, result, cancellationToken);
+    }
+}
diff --git a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
index ca2ac86d3a..6715fdfa74 100644
--- a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/AbpMapperlyQueryProjection_Tests.cs
@@ -15,17 +15,25 @@ public class AbpMapperlyQueryProjection_Tests : AbpIntegratedTest<MapperlyTestMo
     [Fact]
     public void Should_Project_A_Queryable()
     {
-        var projectionMapper = ServiceProvider.GetRequiredService<IQueryableMapper<MyEntity, MyEntityDto>>();
+        var queryProjector = ServiceProvider.GetRequiredService<IQueryProjector<MyEntity, MyEntityDto>>();
 
         var entities = new List<MyEntity>
         {
             new MyEntity { Id = Guid.NewGuid(), Number = 42 }
         }.AsQueryable();
 
-        var dtos = projectionMapper.ProjectTo(entities).ToList();
+        var dtos = queryProjector.ProjectTo(entities).ToList();
 
         dtos.Count.ShouldBe(1);
         dtos[0].Id.ShouldBe(entities.First().Id);
         dtos[0].Number.ShouldBe(42);
     }
+
+
+    [Fact]
+    public void Should_Register_A_Projector_Only_Once()
+    {
+        //MyEntityQueryProjector also matches the class name convention of ExposeServicesAttribute
+        ServiceProvider.GetServices<IQueryProjector<MyEntity, MyEntityDto>>().ShouldHaveSingleItem();
+    }
 }
diff --git a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
index d7ad0fb260..980e40a94b 100644
--- a/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
+++ b/framework/test/Volo.Abp.Mapperly.Tests/Volo/Abp/Mapperly/SampleClasses/MyEntityQueryProjector.cs
@@ -5,7 +5,7 @@ using Volo.Abp.ObjectMapping;
 namespace Volo.Abp.Mapperly.SampleClasses;
 
 [Mapper(RequiredMappingStrategy = RequiredMappingStrategy.Target)]
-public partial class MyEntityQueryProjector : IQueryableMapper<MyEntity, MyEntityDto>
+public partial class MyEntityQueryProjector : IQueryProjector<MyEntity, MyEntityDto>
 {
     public partial IQueryable<MyEntityDto> ProjectTo(IQueryable<MyEntity> source);
 }
diff --git a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
index 341ef77d91..eac0c6fd3a 100644
--- a/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
+++ b/framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Applications/PersonProjector.cs
@@ -4,7 +4,7 @@ using Volo.Abp.TestApp.Domain;
 
 namespace Volo.Abp.MongoDB.Applications;
 
-public class PersonProjector : IQueryableMapper<Person, PersonProjectionDto>
+public class PersonProjector : IQueryProjector<Person, PersonProjectionDto>
 {
     public IQueryable<PersonProjectionDto> ProjectTo(IQueryable<Person> source)
     {

From 7ac1bc668e5aedc20b5cffaedbbf1f465713bb13 Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 15:51:19 +0800
Subject: [PATCH 13/17] Document the query projection

---
 .../application-services.md                   | 51 ++++++++++++++++---
 1 file changed, 44 insertions(+), 7 deletions(-)

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index 5c548820aa..0561dcbd3c 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -1,4 +1,4 @@
-```json
+```json
 //[doc-seo]
 {
     "Description": "Learn how to implement application services in the ABP Framework to expose domain logic and streamline presentation layer interactions."
@@ -444,7 +444,7 @@ These methods are low level methods that can control how to query entities from
 * `ApplyPaging` is used to make paging on the query. If your `TGetListInput` already implements `IPagedResultRequest`, you don't need to override this since the ABP automatically understands it and performs the paging.
 * `ApplySorting` is used to sort (order by...) the query. If your `TGetListInput` already implements the `ISortedResultRequest`, ABP automatically sorts the query. If not, it fallbacks to the `ApplyDefaultSorting` which tries to sort by creation time, if your entity implements the standard `IHasCreationTime` interface.
 * `GetEntityByIdAsync` is used to get an entity by id, which calls `Repository.GetAsync(id)` by default.
-* `CreateEntityQueryAsync` is used to create a query for a single entity by id, which is only needed for the *Query Projection* explained below. It returns `null` if the application service can not create such a query, then `GetEntityByIdAsync` is used.
+* `CreateEntityQueryOrNullAsync` is used to create a query for a single entity by id, which is only needed for the *Query Projection* explained below. It returns `null` if the application service can not create such a query, then `GetEntityByIdAsync` is used.
 * `DeleteByIdAsync` is used to delete an entity by id, which calls `Repository.DeleteAsync(id)` by default.
 
 #### Object to Object Mapping
@@ -461,7 +461,7 @@ These methods are used to convert Entities to DTOs and vice verse. They use the
 
 `GetAsync` and `GetListAsync` get the entities from the database, then map them to DTOs in the memory. If your DTO uses only a few properties of a large entity, you can project the query to the DTO instead, so the database returns only the columns you need.
 
-Implement the `IQueryableMapper<TEntity, TDto>` interface to define a projection:
+Implement the `IQueryProjector<TEntity, TDto>` interface to define a projection:
 
 ````csharp
 using System.Linq;
@@ -469,7 +469,7 @@ using Volo.Abp.ObjectMapping;
 
 namespace MyProject.Books;
 
-public class BookProjector : IQueryableMapper<Book, BookDto>
+public class BookProjector : IQueryProjector<Book, BookDto>
 {
     public IQueryable<BookDto> ProjectTo(IQueryable<Book> source)
     {
@@ -484,14 +484,51 @@ public class BookProjector : IQueryableMapper<Book, BookDto>
 
 You don't have to write the `Select` by hand. Both [Mapperly](https://mapperly.riok.app/) and [AutoMapper](https://docs.automapper.org) can project an `IQueryable`, refer to their own documentation for it and to the [object to object mapping document](../../infrastructure/object-to-object-mapping.md) for their ABP integrations.
 
-ABP registers the projection mappers by convention, you don't need to configure anything else. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
+ABP registers the projectors by convention, you don't need to configure anything else. Implement a projector once for an entity and DTO pair, the last registered one is used otherwise. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
 
-> The projection replaces the entity based extension points. `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync`, `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore. If an application service needs to keep using them, override the `GetQueryableMapper` or `GetListQueryableMapper` property and return `null`:
+> A projection must return one row per entity. The total count and the paging are calculated on the entity query before the projection runs, so a projection that filters out rows (an inner join to an optional relation) or multiplies them (a join to a collection) returns a page that doesn't match the reported total count. Use a left join for optional relations.
+
+The projector is synchronous, so it can not obtain the query of another aggregate root, which is only
+available through the asynchronous `GetQueryableAsync`. Override `CreateGetOutputDtoQueryOrNullAsync` or
+`CreateGetListOutputDtoQueryOrNullAsync` for that. They replace the projector for that application service:
+
+````csharp
+public class BookAppService : ReadOnlyAppService<Book, BookDto, Guid>
+{
+    private readonly IReadOnlyRepository<Author, Guid> _authorRepository;
+
+    //...
+
+    protected override async Task<IQueryable<BookDto>?> CreateGetListOutputDtoQueryOrNullAsync(IQueryable<Book> query)
+    {
+        var authors = await _authorRepository.GetQueryableAsync();
+
+        return from book in query
+               join author in authors on book.AuthorId equals author.Id into bookAuthors
+               from bookAuthor in bookAuthors.DefaultIfEmpty()
+               select new BookDto
+               {
+                   Id = book.Id,
+                   Name = book.Name,
+                   AuthorName = bookAuthor != null ? bookAuthor.Name : null
+               };
+    }
+}
+````
+
+Both queries must come from the same database context, otherwise they can not be executed as a single query,
+and the provider has to be able to translate the join. The one row per entity rule above applies here too,
+that's why the example uses a left join. A joined column can not be used for the sorting and the paging,
+since they are already applied to the entity query before this method is called.
+
+> The projection replaces the entity based extension points. `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync`, `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore. Projectors are resolved by the `(entity, DTO)` type pair, so registering one enables the projection for every application service using that pair. If an application service needs to keep using the entity based extension points, override the `GetOutputDtoQueryProjector` or `GetListOutputDtoQueryProjector` property and return `null`:
 
 ````csharp
 public class BookAppService : CrudAppService<Book, BookDto, Guid>
 {
-    protected override IQueryableMapper<Book, BookDto>? GetQueryableMapper => null;
+    protected override IQueryProjector<Book, BookDto>? GetOutputDtoQueryProjector => null;
+
+    protected override IQueryProjector<Book, BookDto>? GetListOutputDtoQueryProjector => null;
 
     //...
 }

From c24a0e3b500173c64b20f9cd8b45132ecdae078c Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 16:12:37 +0800
Subject: [PATCH 14/17] Keep checking the authorization policies while
 projecting

* The projection only replaces the DTO creation, the filters and the policies still apply
---
 .../application-services.md                   |  9 +++++-
 .../BookPolicyCheckedAppService.cs            | 29 +++++++++++++++++++
 .../QueryProjection/QueryProjection_Tests.cs  | 10 +++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookPolicyCheckedAppService.cs

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index 0561dcbd3c..c257a613f7 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -521,7 +521,14 @@ and the provider has to be able to translate the join. The one row per entity ru
 that's why the example uses a left join. A joined column can not be used for the sorting and the paging,
 since they are already applied to the entity query before this method is called.
 
-> The projection replaces the entity based extension points. `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync`, `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore. Projectors are resolved by the `(entity, DTO)` type pair, so registering one enables the projection for every application service using that pair. If an application service needs to keep using the entity based extension points, override the `GetOutputDtoQueryProjector` or `GetListOutputDtoQueryProjector` property and return `null`:
+A projector is resolved by the `(entity, DTO)` type pair, just like an `IObjectMapper<TSource, TDestination>`, so registering one enables the projection for every application service using that pair. The projection only replaces the way the DTOs are created:
+
+* `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync` anymore.
+* `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore.
+
+Everything else is untouched. The authorization policies are still checked, `CreateFilteredQueryAsync`, `ApplySorting` and `ApplyPaging` are still used, the data filters (like soft delete and multi-tenancy) are still applied, and the create, update and delete methods still use the [IObjectMapper](../../infrastructure/object-to-object-mapping.md).
+
+> If an application service needs to keep using the entity based extension points, override the `GetOutputDtoQueryProjector` or `GetListOutputDtoQueryProjector` property and return `null`:
 
 ````csharp
 public class BookAppService : CrudAppService<Book, BookDto, Guid>
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookPolicyCheckedAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookPolicyCheckedAppService.cs
new file mode 100644
index 0000000000..ee8e73db14
--- /dev/null
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookPolicyCheckedAppService.cs
@@ -0,0 +1,29 @@
+using System;
+using System.Threading.Tasks;
+using Volo.Abp.Domain.Repositories;
+
+namespace Volo.Abp.Application.Services.QueryProjection;
+
+public class BookPolicyCheckedException : Exception
+{
+
+}
+
+public class BookPolicyCheckedAppService : CrudAppService<Book, BookDto, Guid>
+{
+    public BookPolicyCheckedAppService(IRepository<Book, Guid> repository)
+        : base(repository)
+    {
+
+    }
+
+    protected override Task CheckGetPolicyAsync()
+    {
+        throw new BookPolicyCheckedException();
+    }
+
+    protected override Task CheckGetListPolicyAsync()
+    {
+        throw new BookPolicyCheckedException();
+    }
+}
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
index 228e4591c3..3823a07a56 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
@@ -178,4 +178,14 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
 
         (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookProjector.Marker);
     }
+
+    [Fact]
+    public async Task Should_Check_The_Policies_While_Projecting()
+    {
+        var appService = GetRequiredService<BookPolicyCheckedAppService>();
+
+        await Should.ThrowAsync<BookPolicyCheckedException>(async () => await appService.GetAsync(_bookId));
+        await Should.ThrowAsync<BookPolicyCheckedException>(async () =>
+            await appService.GetListAsync(new PagedAndSortedResultRequestDto()));
+    }
 }

From be8f078ea9662630b310fa4a7da5256a149f603d Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 17:35:04 +0800
Subject: [PATCH 15/17] Keep the ambient cancellation token out of the entity
 paths

* Only the projected GetAsync passes it, that is the path Repository.GetAsync already covered
* Assert a single data query so a materialize-then-project implementation can not pass
* Opting out of the projection brings the entity based overrides back
---
 .../Services/AbstractKeyReadOnlyAppService.cs | 12 +++---
 .../Services/ApplicationService.cs            |  3 --
 .../ObjectMapping/AbpObjectMappingModule.cs   |  1 -
 .../Volo/Abp/ObjectMapping/IQueryProjector.cs |  3 +-
 .../BookCustomizedAppService.cs               |  6 +++
 .../BookWithoutProjectionAppService.cs        | 14 +++++++
 .../QueryProjection/QueryProjection_Tests.cs  | 11 +++--
 .../Applications/PersonWithCityDto.cs         |  3 +-
 .../Applications/QueryProjection_Tests.cs     | 41 ++++++++++++++-----
 9 files changed, 70 insertions(+), 24 deletions(-)

diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
index e4980074ba..fa8aafc76a 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs
@@ -92,7 +92,7 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
         await CheckGetListPolicyAsync();
 
         var query = await CreateFilteredQueryAsync(input);
-        var totalCount = await AsyncExecuter.CountAsync(query, GetCancellationToken());
+        var totalCount = await AsyncExecuter.CountAsync(query);
 
         var entityDtos = new List<TGetListOutputDto>();
 
@@ -104,11 +104,11 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
             var dtoQuery = await CreateGetListOutputDtoQueryOrNullAsync(query);
             if (dtoQuery != null)
             {
-                entityDtos = await AsyncExecuter.ToListAsync(dtoQuery, GetCancellationToken());
+                entityDtos = await AsyncExecuter.ToListAsync(dtoQuery);
             }
             else
             {
-                var entities = await AsyncExecuter.ToListAsync(query, GetCancellationToken());
+                var entities = await AsyncExecuter.ToListAsync(query);
                 entityDtos = await MapToGetListOutputDtosAsync(entities);
             }
         }
@@ -121,9 +121,11 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
 
     protected abstract Task<TEntity> GetEntityByIdAsync(TKey id);
 
-    protected virtual CancellationToken GetCancellationToken(CancellationToken preferredValue = default)
+    private CancellationToken GetCancellationToken()
     {
-        return CancellationTokenProvider.FallbackToProvider(preferredValue);
+        return LazyServiceProvider
+            .LazyGetService<ICancellationTokenProvider>(NullCancellationTokenProvider.Instance)
+            .FallbackToProvider();
     }
 
     /// <summary>
diff --git a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs
index 01e9e81354..4eb285df04 100644
--- a/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs
+++ b/framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ApplicationService.cs
@@ -19,7 +19,6 @@ using Volo.Abp.Localization;
 using Volo.Abp.MultiTenancy;
 using Volo.Abp.ObjectMapping;
 using Volo.Abp.Settings;
-using Volo.Abp.Threading;
 using Volo.Abp.Timing;
 using Volo.Abp.Uow;
 using Volo.Abp.Users;
@@ -49,8 +48,6 @@ public abstract class ApplicationService :
 
     protected IAsyncQueryableExecuter AsyncExecuter => LazyServiceProvider.LazyGetRequiredService<IAsyncQueryableExecuter>();
 
-    protected ICancellationTokenProvider CancellationTokenProvider => LazyServiceProvider.LazyGetService<ICancellationTokenProvider>(NullCancellationTokenProvider.Instance);
-
     protected Type? ObjectMapperContext { get; set; }
     protected IObjectMapper ObjectMapper => LazyServiceProvider.LazyGetService<IObjectMapper>(provider =>
         ObjectMapperContext == null
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
index 87e0c43b56..2f1b8830ac 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs
@@ -21,7 +21,6 @@ public class AbpObjectMappingModule : AbpModule
             );
 
             //Register types for IQueryProjector<TSource, TDestination> if implements
-            //The class name convention may have already exposed them, so they are not added twice
             foreach (var serviceType in ReflectionHelper.GetImplementedGenericTypes(
                          onServiceExposingContext.ImplementationType,
                          typeof(IQueryProjector<,>)))
diff --git a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjector.cs b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjector.cs
index 1abf5667e6..89652e5f40 100644
--- a/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjector.cs
+++ b/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/IQueryProjector.cs
@@ -7,7 +7,8 @@ namespace Volo.Abp.ObjectMapping;
 /// Maps a query to another.
 /// Implement this interface to project a query on the data store side, instead of loading the
 /// source objects into the memory and mapping them one by one.
-/// Implement it once for a source and destination pair, the last registered one is used otherwise.
+/// Implement it once for a source and destination pair. Use the ReplaceServices option of the
+/// DependencyAttribute to replace an existing implementation.
 /// </summary>
 /// <typeparam name="TSource">Type of the source objects</typeparam>
 /// <typeparam name="TDestination">Type of the destination objects</typeparam>
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs
index b4c756d6b2..f5df26baaa 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookCustomizedAppService.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Volo.Abp.Domain.Repositories;
 
@@ -25,4 +26,9 @@ public class BookCustomizedAppService : CrudAppService<Book, BookDto, Guid>
     {
         return Task.FromResult(new BookDto { Id = entity.Id, Name = entity.Name + Marker });
     }
+
+    protected override Task<List<BookDto>> MapToGetListOutputDtosAsync(List<Book> entities)
+    {
+        return Task.FromResult(entities.ConvertAll(entity => new BookDto { Id = entity.Id, Name = entity.Name + Marker }));
+    }
 }
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
index 9ad4680d45..928c8fee66 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/BookWithoutProjectionAppService.cs
@@ -1,5 +1,7 @@
 #nullable enable
 using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
 using Volo.Abp.Domain.Repositories;
 using Volo.Abp.ObjectMapping;
 
@@ -7,6 +9,8 @@ namespace Volo.Abp.Application.Services.QueryProjection;
 
 public class BookWithoutProjectionAppService : CrudAppService<Book, BookDto, Guid>
 {
+    public const string Marker = "-not-projected";
+
     protected override IQueryProjector<Book, BookDto>? GetOutputDtoQueryProjector => null;
 
     protected override IQueryProjector<Book, BookDto>? GetListOutputDtoQueryProjector => null;
@@ -16,4 +20,14 @@ public class BookWithoutProjectionAppService : CrudAppService<Book, BookDto, Gui
     {
 
     }
+
+    protected override Task<BookDto> MapToGetOutputDtoAsync(Book entity)
+    {
+        return Task.FromResult(new BookDto { Id = entity.Id, Name = entity.Name + Marker });
+    }
+
+    protected override Task<List<BookDto>> MapToGetListOutputDtosAsync(List<Book> entities)
+    {
+        return Task.FromResult(entities.ConvertAll(entity => new BookDto { Id = entity.Id, Name = entity.Name + Marker }));
+    }
 }
diff --git a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
index 3823a07a56..425021fb03 100644
--- a/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.Ddd.Application.Tests/Volo/Abp/Application/Services/QueryProjection/QueryProjection_Tests.cs
@@ -66,13 +66,13 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
     }
 
     [Fact]
-    public async Task Should_Use_The_Object_Mapper_If_The_Projection_Was_Disabled()
+    public async Task Should_Use_The_Entity_Based_Overrides_If_The_Projection_Was_Disabled()
     {
         var appService = GetRequiredService<BookWithoutProjectionAppService>();
 
-        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookObjectMapper.Marker);
+        (await appService.GetAsync(_bookId)).Name.ShouldEndWith(BookWithoutProjectionAppService.Marker);
         (await appService.GetListAsync(new PagedAndSortedResultRequestDto()))
-            .Items[0].Name.ShouldEndWith(BookObjectMapper.Marker);
+            .Items[0].Name.ShouldEndWith(BookWithoutProjectionAppService.Marker);
     }
 
     [Fact]
@@ -84,6 +84,11 @@ public class QueryProjection_Tests : AbpDddApplicationTestBase
 
         dto.Name.ShouldEndWith(BookProjector.Marker);
         dto.Name.ShouldNotContain(BookCustomizedAppService.Marker);
+
+        var items = (await appService.GetListAsync(new PagedAndSortedResultRequestDto())).Items;
+
+        items[0].Name.ShouldEndWith(BookProjector.Marker);
+        items[0].Name.ShouldNotContain(BookCustomizedAppService.Marker);
     }
 
     [Fact]
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs
index db62825b8e..dac278c7b6 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/PersonWithCityDto.cs
@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using Volo.Abp.Application.Dtos;
 
@@ -7,5 +8,5 @@ public class PersonWithCityDto : EntityDto<Guid>
 {
     public string Name { get; set; }
 
-    public string CityName { get; set; }
+    public string? CityName { get; set; }
 }
diff --git a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
index e2d2f45d7c..d4410c15e7 100644
--- a/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
+++ b/framework/test/Volo.Abp.EntityFrameworkCore.Tests/Volo/Abp/EntityFrameworkCore/Applications/QueryProjection_Tests.cs
@@ -129,8 +129,9 @@ public class QueryProjection_Tests : EntityFrameworkCoreTestBase
         }
 
         //the application service must run the projection itself, not materialize the entities first
-        var select = commands.Last(x => x.Contains("FROM \"People\"") && !x.Contains("COUNT"));
+        var selects = commands.Where(x => x.Contains("FROM \"People\"") && !x.Contains("COUNT")).ToList();
 
+        var select = selects.ShouldHaveSingleItem();
         select.ShouldContain("\"Name\"");
         select.ShouldNotContain("\"Birthday\"");
         select.ShouldNotContain("\"ExtraProperties\"");
@@ -151,26 +152,46 @@ public class QueryProjection_Tests : EntityFrameworkCoreTestBase
         var cancellationTokenProvider = GetRequiredService<ICancellationTokenProvider>();
         var appService = GetRequiredService<PersonProjectionAppService>();
 
+        //the entity path passes it through Repository.GetAsync, so the projected path must not regress
         using (cancellationTokenProvider.Use(new CancellationToken(canceled: true)))
         {
             await Should.ThrowAsync<OperationCanceledException>(async () =>
                 await appService.GetAsync(TestDataBuilder.UserDouglasId));
+        }
+    }
 
-            await Should.ThrowAsync<OperationCanceledException>(async () =>
-                await appService.GetListAsync(new PagedAndSortedResultRequestDto()));
+    [Fact]
+    public async Task Should_Execute_The_Projected_Query_From_The_Application_Service_For_A_Single_Entity()
+    {
+        System.Collections.Concurrent.ConcurrentQueue<string> commands;
+        using (SqlCommandCapture.Begin(out commands))
+        {
+            await GetRequiredService<PersonProjectionAppService>().GetAsync(TestDataBuilder.UserDouglasId);
         }
+
+        var selects = commands.Where(x => x.Contains("FROM \"People\"")).ToList();
+
+        var select = selects.ShouldHaveSingleItem();
+        select.ShouldContain("\"Name\"");
+        select.ShouldNotContain("\"Birthday\"");
+        select.ShouldNotContain("\"ExtraProperties\"");
     }
 
     [Fact]
-    public async Task Should_Use_The_Ambient_Cancellation_Token_Without_A_Projector()
+    public async Task Should_Apply_The_Data_Filters_Of_The_Joined_Aggregate()
     {
-        var cancellationTokenProvider = GetRequiredService<ICancellationTokenProvider>();
-        var appService = GetRequiredService<IPeopleAppService>();
+        var cityRepository = GetRequiredService<IRepository<City, Guid>>();
 
-        using (cancellationTokenProvider.Use(new CancellationToken(canceled: true)))
+        await WithUnitOfWorkAsync(async () =>
         {
-            await Should.ThrowAsync<OperationCanceledException>(async () =>
-                await appService.GetListAsync(new PagedAndSortedResultRequestDto()));
-        }
+            var london = await cityRepository.GetAsync(TestDataBuilder.LondonCityId);
+            await cityRepository.DeleteAsync(london, autoSave: true);
+        });
+
+        var result = await GetRequiredService<PersonWithCityAppService>()
+            .GetListAsync(new PagedAndSortedResultRequestDto());
+
+        //the soft deleted city is filtered out, the left join still keeps the person
+        result.Items.ShouldContain(x => x.Name == "Douglas" && x.CityName == null);
     }
 }

From dfeb830255b431744aead36626bd5d8f1a707209 Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 17:35:04 +0800
Subject: [PATCH 16/17] Clarify the query projection contract in the
 documentation

---
 .../domain-driven-design/application-services.md     | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index c257a613f7..57c104385e 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -484,7 +484,7 @@ public class BookProjector : IQueryProjector<Book, BookDto>
 
 You don't have to write the `Select` by hand. Both [Mapperly](https://mapperly.riok.app/) and [AutoMapper](https://docs.automapper.org) can project an `IQueryable`, refer to their own documentation for it and to the [object to object mapping document](../../infrastructure/object-to-object-mapping.md) for their ABP integrations.
 
-ABP registers the projectors by convention, you don't need to configure anything else. Implement a projector once for an entity and DTO pair, the last registered one is used otherwise. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
+ABP registers the projectors by convention, you don't need to configure anything else. Implement a projector once for an entity and DTO pair, and use the `ReplaceServices` option of the `DependencyAttribute` to replace an existing one. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
 
 > A projection must return one row per entity. The total count and the paging are calculated on the entity query before the projection runs, so a projection that filters out rows (an inner join to an optional relation) or multiplies them (a join to a collection) returns a page that doesn't match the reported total count. Use a left join for optional relations.
 
@@ -518,15 +518,15 @@ public class BookAppService : ReadOnlyAppService<Book, BookDto, Guid>
 
 Both queries must come from the same database context, otherwise they can not be executed as a single query,
 and the provider has to be able to translate the join. The one row per entity rule above applies here too,
-that's why the example uses a left join. A joined column can not be used for the sorting and the paging,
-since they are already applied to the entity query before this method is called.
+that's why the example uses a left join. A joined column can not be used for the sorting, and the paging is
+based on the entity query, since both are applied before this method is called.
 
-A projector is resolved by the `(entity, DTO)` type pair, just like an `IObjectMapper<TSource, TDestination>`, so registering one enables the projection for every application service using that pair. The projection only replaces the way the DTOs are created:
+A projector is resolved by the `(entity, DTO)` type pair, just like an `IObjectMapper<TSource, TDestination>`, so registering one enables the projection for every application service using that pair. It replaces the way the DTOs are read:
 
-* `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync` anymore.
 * `GetListAsync` doesn't use `MapToGetListOutputDtosAsync` anymore.
+* `GetAsync` doesn't use `GetEntityByIdAsync` and `MapToGetOutputDtoAsync` anymore, as long as the application service can create a query for a single entity. `ReadOnlyAppService` and `CrudAppService` already do that. A class deriving from `AbstractKeyReadOnlyAppService` has to override `CreateEntityQueryOrNullAsync`, otherwise `GetAsync` keeps loading the entity and mapping it.
 
-Everything else is untouched. The authorization policies are still checked, `CreateFilteredQueryAsync`, `ApplySorting` and `ApplyPaging` are still used, the data filters (like soft delete and multi-tenancy) are still applied, and the create, update and delete methods still use the [IObjectMapper](../../infrastructure/object-to-object-mapping.md).
+The rest of the pipeline is untouched. The authorization policies are still checked, `CreateFilteredQueryAsync`, `ApplySorting` and `ApplyPaging` are still used, the data filters (like soft delete and multi-tenancy) are still applied, and the create, update and delete methods still use the [IObjectMapper](../../infrastructure/object-to-object-mapping.md).
 
 > If an application service needs to keep using the entity based extension points, override the `GetOutputDtoQueryProjector` or `GetListOutputDtoQueryProjector` property and return `null`:
 

From c0b78d863287b3f777a3839088e277d501e5f936 Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 20 Aug 2026 19:59:38 +0800
Subject: [PATCH 17/17] Show a reusable projection in the asynchronous hook
 sample

---
 .../application-services.md                   | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/docs/en/framework/architecture/domain-driven-design/application-services.md b/docs/en/framework/architecture/domain-driven-design/application-services.md
index 57c104385e..a2d2db5acc 100644
--- a/docs/en/framework/architecture/domain-driven-design/application-services.md
+++ b/docs/en/framework/architecture/domain-driven-design/application-services.md
@@ -482,7 +482,7 @@ public class BookProjector : IQueryProjector<Book, BookDto>
 }
 ````
 
-You don't have to write the `Select` by hand. Both [Mapperly](https://mapperly.riok.app/) and [AutoMapper](https://docs.automapper.org) can project an `IQueryable`, refer to their own documentation for it and to the [object to object mapping document](../../infrastructure/object-to-object-mapping.md) for their ABP integrations.
+You don't have to write the `Select` by hand. Both [Mapperly](https://mapperly.riok.app/) and [AutoMapper](https://docs.automapper.org) can project an `IQueryable`, refer to their own documentation for it and to the [object to object mapping document](../../infrastructure/object-to-object-mapping.md) for their ABP integrations. Your existing maps are not used for the projection, a projector is always a class implementing `IQueryProjector<TSource, TDestination>`.
 
 ABP registers the projectors by convention, you don't need to configure anything else. Implement a projector once for an entity and DTO pair, and use the `ReplaceServices` option of the `DependencyAttribute` to replace an existing one. Filters (like soft delete and multi-tenancy), sorting and paging are still applied to the query before the projection.
 
@@ -495,15 +495,28 @@ available through the asynchronous `GetQueryableAsync`. Override `CreateGetOutpu
 ````csharp
 public class BookAppService : ReadOnlyAppService<Book, BookDto, Guid>
 {
-    private readonly IReadOnlyRepository<Author, Guid> _authorRepository;
+    private readonly IBookDtoQuery _bookDtoQuery;
 
     //...
 
     protected override async Task<IQueryable<BookDto>?> CreateGetListOutputDtoQueryOrNullAsync(IQueryable<Book> query)
+    {
+        return await _bookDtoQuery.ProjectAsync(query);
+    }
+}
+
+//The projection is a class of its own, so the other application services returning a BookDto reuse it
+public class BookDtoQuery : IBookDtoQuery, ITransientDependency
+{
+    private readonly IReadOnlyRepository<Author, Guid> _authorRepository;
+
+    //...
+
+    public async Task<IQueryable<BookDto>> ProjectAsync(IQueryable<Book> books)
     {
         var authors = await _authorRepository.GetQueryableAsync();
 
-        return from book in query
+        return from book in books
                join author in authors on book.AuthorId equals author.Id into bookAuthors
                from bookAuthor in bookAuthors.DefaultIfEmpty()
                select new BookDto