feat: add IQueryable DTO projection support to read-only application services

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);
     }
-}
+}

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);
         }
     }
-}
+}

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);
+}

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);
+}