Mapster.EF.Core: Add type check for IAsyncEnumerable<>

src/Mapster.EFCore.Tests/EFCoreTest.cs

@@ -6,6 +6,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 
 namespace Mapster.EFCore.Tests
 {
@@ -45,6 +46,34 @@ public void TestFindObject()
             first.Grade.ShouldBe(Grade.F);
         }
 
+        [TestMethod]
+        public async Task TestFindSingleObjectUsingProjectToType()
+        {
+            var options = new DbContextOptionsBuilder<SchoolContext>()
+                .UseInMemoryDatabase(Guid.NewGuid().ToString("N"))
+                .Options;
+            var context = new SchoolContext(options);
+            DbInitializer.Initialize(context);
+
+            var mapsterInstance = new Mapper();
+
+            var query = context.Students.Where(s => s.ID == 1);
+
+            async Task<StudentDto> FirstExecute() =>
+                await mapsterInstance.From(query)
+                    .ProjectToType<StudentDto>()
+                    .FirstOrDefaultAsync();
+
+            await Should.NotThrowAsync(async () =>
+            {
+                var first = await FirstExecute();
+
+                first.ShouldNotBeNull();
+                first.ID.ShouldBe(1);
+                first.LastName.ShouldBe("Alexander");
+            });
+        }
+
         [TestMethod]
         public void MapperInstance_From_OrderBy()
         {

src/Mapster.EFCore/MapsterQueryable.cs

@@ -82,11 +82,21 @@ public TResult ExecuteAsync<TResult>(Expression expression, CancellationToken ca
         {
             var enumerable = ((IAsyncQueryProvider)_provider).ExecuteAsync<TResult>(expression, cancellationToken);
             var enumerableType = typeof(TResult);
+            if (!IsAsyncEnumerableType(enumerableType))
+            {
+                return enumerable;
+            }
             var elementType = enumerableType.GetGenericArguments()[0];
             var wrapType = typeof(MapsterAsyncEnumerable<>).MakeGenericType(elementType);
             return (TResult) Activator.CreateInstance(wrapType, enumerable, _builder);
         }
 
+        private static bool IsAsyncEnumerableType(Type type)
+        {
+            return type.GetInterfaces()
+                .Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(IAsyncEnumerable<>));
+        }
+
         public IAsyncEnumerable<TResult> ExecuteEnumerableAsync<TResult>(Expression expression, CancellationToken cancellationToken = default)
         {
             var enumerable = ((IAsyncQueryProvider)_provider).ExecuteAsync<IAsyncEnumerable<TResult>>(expression, cancellationToken);