Add `ExistAsync` and `FindAsync` methods to `IReadOnlyAppService`.

framework/src/Volo.Abp.Ddd.Application.Contracts/Volo/Abp/Application/Services/IReadOnlyAppService.cs

@@ -1,4 +1,5 @@
-using System.Threading.Tasks;
+using System.Threading;
+using System.Threading.Tasks;
 using Volo.Abp.Application.Dtos;
 
 namespace Volo.Abp.Application.Services;
@@ -18,6 +19,10 @@ public interface IReadOnlyAppService<TEntityDto, in TKey, in TGetListInput>
 public interface IReadOnlyAppService<TGetOutputDto, TGetListOutputDto, in TKey, in TGetListInput>
     : IApplicationService
 {
+    Task<bool> ExistsAsync(TKey id);
+
+    Task<TGetListOutputDto?> FindAsync(TKey id);
+
     Task<TGetOutputDto> GetAsync(TKey id);
 
     Task<PagedResultDto<TGetListOutputDto>> GetListAsync(TGetListInput input);

framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/AbstractKeyReadOnlyAppService.cs

@@ -49,6 +49,22 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
         ReadOnlyRepository = repository;
     }
 
+    public virtual async Task<bool> ExistsAsync(TKey id)
+    {
+        await CheckGetPolicyAsync();
+
+        return await ExistAsync(id);
+    }
+
+    public virtual async Task<TGetListOutputDto?> FindAsync(TKey id)
+    {
+        await CheckGetPolicyAsync();
+
+        var entity = await FindEntityByIdAsync(id);
+
+        return entity == null ? default : await MapToGetListOutputDtoAsync(entity);
+    }
+
     public virtual async Task<TGetOutputDto> GetAsync(TKey id)
     {
         await CheckGetPolicyAsync();
@@ -83,6 +99,10 @@ public abstract class AbstractKeyReadOnlyAppService<TEntity, TGetOutputDto, TGet
         );
     }
 
+    protected abstract Task<bool> ExistAsync(TKey id);
+
+    protected abstract Task<TEntity?> FindEntityByIdAsync(TKey id);
+
     protected abstract Task<TEntity> GetEntityByIdAsync(TKey id);
 
     protected virtual async Task CheckGetPolicyAsync()

framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/CrudAppService.cs

@@ -74,12 +74,22 @@ public abstract class CrudAppService<TEntity, TGetOutputDto, TGetListOutputDto,
         Repository = repository;
     }
 
-    protected override async Task DeleteByIdAsync(TKey id)
+    protected async override Task<bool> ExistAsync(TKey id)
+    {
+        return await Repository.AnyAsync(x => x.Id!.Equals(id));
+    }
+
+    protected async override Task<TEntity?> FindEntityByIdAsync(TKey id)
+    {
+        return await Repository.FindAsync(id);
+    }
+
+    protected async override Task DeleteByIdAsync(TKey id)
     {
         await Repository.DeleteAsync(id);
     }
 
-    protected override async Task<TEntity> GetEntityByIdAsync(TKey id)
+    protected async override Task<TEntity> GetEntityByIdAsync(TKey id)
     {
         return await Repository.GetAsync(id);
     }

framework/src/Volo.Abp.Ddd.Application/Volo/Abp/Application/Services/ReadOnlyAppService.cs

@@ -42,7 +42,17 @@ public abstract class ReadOnlyAppService<TEntity, TGetOutputDto, TGetListOutputD
         Repository = repository;
     }
 
-    protected override async Task<TEntity> GetEntityByIdAsync(TKey id)
+    protected override Task<bool> ExistAsync(TKey id)
+    {
+        return Repository.AnyAsync(x => x.Id!.Equals(id));
+    }
+
+    protected override Task<TEntity?> FindEntityByIdAsync(TKey id)
+    {
+        return Repository.FindAsync(id);
+    }
+
+    protected async override Task<TEntity > GetEntityByIdAsync(TKey id)
     {
         return await Repository.GetAsync(id);
     }

framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Application/DistrictAppService.cs

@@ -15,12 +15,26 @@ public class DistrictAppService : AbstractKeyCrudAppService<District, DistrictDt
     {
     }
 
-    protected override async Task DeleteByIdAsync(DistrictKey id)
+    protected async override Task DeleteByIdAsync(DistrictKey id)
     {
         await Repository.DeleteAsync(d => d.CityId == id.CityId && d.Name == id.Name);
     }
 
-    protected override async Task<District> GetEntityByIdAsync(DistrictKey id)
+    protected async override Task<bool> ExistAsync(DistrictKey id)
+    {
+        return await AsyncExecuter.AnyAsync(
+            (await Repository.GetQueryableAsync()).Where(d => d.CityId == id.CityId && d.Name == id.Name)
+        );
+    }
+
+    protected async override Task<District> FindEntityByIdAsync(DistrictKey id)
+    {
+        return await AsyncExecuter.FirstOrDefaultAsync(
+            (await Repository.GetQueryableAsync()).Where(d => d.CityId == id.CityId && d.Name == id.Name)
+        );
+    }
+
+    protected async override Task<District> GetEntityByIdAsync(DistrictKey id)
     {
         return await AsyncExecuter.FirstOrDefaultAsync(
              (await Repository.GetQueryableAsync()).Where(d => d.CityId == id.CityId && d.Name == id.Name)