Complete only the reserved unit of work on response start

framework/src/Volo.Abp.AspNetCore/Volo/Abp/AspNetCore/Uow/AbpUnitOfWorkMiddleware.cs

@@ -39,12 +39,13 @@ public class AbpUnitOfWorkMiddleware : AbpMiddlewareBase, ITransientDependency
         {
             // Commit the ambient unit of work before the response starts, so data written
             // during the request is committed before the response is flushed to the client.
+            // Only when this reserved unit of work is the current one: if an explicit nested
+            // unit of work is in progress, it is the current one and must be left to its owner.
             context.Response.OnStarting(async () =>
             {
-                var currentUow = _unitOfWorkManager.Current;
-                if (currentUow != null && !currentUow.IsCompleted)
+                if (_unitOfWorkManager.Current == uow)
                 {
-                    await currentUow.CompleteAsync(_cancellationTokenProvider.Token);
+                    await uow.CompleteAsync(_cancellationTokenProvider.Token);
                 }
             });
 

framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/Uow/UnitOfWorkMiddleware_Tests.cs

@@ -68,4 +68,11 @@ public class UnitOfWorkMiddleware_Tests : AspNetCoreMvcTestBase
         var body = await GetResponseAsStringAsync("/api/unitofwork-test/RawDatabaseProviderAfterResponseFlush");
         body.ShouldBe("first:threw-AbpException");
     }
+
+    [Fact]
+    public async Task Response_Flush_Inside_Nested_Uow_Should_Not_Complete_The_Nested_Uow()
+    {
+        var body = await GetResponseAsStringAsync("/api/unitofwork-test/NestedUowDuringResponseFlush");
+        body.ShouldBe("first:nested-completed-by-owner");
+    }
 }

framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/Uow/UnitOfWorkTestController.cs

@@ -151,4 +151,28 @@ public class UnitOfWorkTestController : AbpController
 
         await Response.WriteAsync(outcome);
     }
+
+    [HttpGet]
+    [Route("NestedUowDuringResponseFlush")]
+    public async Task NestedUowDuringResponseFlush()
+    {
+        using (var nested = UnitOfWorkManager.Begin(requiresNew: true, isTransactional: false))
+        {
+            await Response.WriteAsync("first");
+            await Response.Body.FlushAsync();
+
+            string outcome;
+            try
+            {
+                await nested.CompleteAsync();
+                outcome = ":nested-completed-by-owner";
+            }
+            catch (AbpException)
+            {
+                outcome = ":nested-already-completed";
+            }
+
+            await Response.WriteAsync(outcome);
+        }
+    }
 }