Make DefaultApiDescriptionProvider understand ActionResult<T>

Fixes #6784
aspnet · Sep 8, 2017 · 656f35d · 656f35d
1 parent 717f1e6
commit 656f35d
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Showing 2 changed files with 55 additions and 11 deletions.
diff --git a/src/Microsoft.AspNetCore.Mvc.ApiExplorer/DefaultApiDescriptionProvider.cs b/src/Microsoft.AspNetCore.Mvc.ApiExplorer/DefaultApiDescriptionProvider.cs
@@ -193,8 +193,7 @@ private IList<ApiParameterDescription> GetParameters(ApiParameterContext context
                     parameter.Source == BindingSource.ModelBinding ||
                     parameter.Source == BindingSource.Custom)
                 {
-                    ApiParameterRouteInfo routeInfo;
-                    if (routeParameters.TryGetValue(parameter.Name, out routeInfo))
+                    if (routeParameters.TryGetValue(parameter.Name, out var routeInfo))
                     {
                         parameter.RouteInfo = routeInfo;
                         routeParameters.Remove(parameter.Name);
@@ -322,8 +321,7 @@ private IReadOnlyList<ApiRequestFormat> GetRequestFormats(
             {
                 foreach (var formatter in _inputFormatters)
                 {
-                    var requestFormatMetadataProvider = formatter as IApiRequestFormatMetadataProvider;
-                    if (requestFormatMetadataProvider != null)
+                    if (formatter is IApiRequestFormatMetadataProvider requestFormatMetadataProvider)
                     {
                         var supportedTypes = requestFormatMetadataProvider.GetSupportedContentTypes(contentType, type);
 
@@ -445,7 +443,10 @@ private Type GetDeclaredReturnType(ControllerActionDescriptor action)
             }
 
             // Unwrap the type if it's a Task<T>. The Task (non-generic) case was already handled.
-            var unwrappedType = GetTaskInnerTypeOrNull(declaredReturnType) ?? declaredReturnType;
+            var unwrappedType = UnwrapGenericType(declaredReturnType, typeof(Task<>));
+
+            // UnWrap the type if it's ActionResult<T> or Task<ActionResult<T>>.
+            unwrappedType = UnwrapGenericType(unwrappedType, typeof(ActionResult<>));
 
             // If the method is declared to return IActionResult or a derived class, that information
             // isn't valuable to the formatter.
@@ -457,13 +458,12 @@ private Type GetDeclaredReturnType(ControllerActionDescriptor action)
             {
                 return unwrappedType;
             }
-        }
-
-        private static Type GetTaskInnerTypeOrNull(Type type)
-        {
-            var genericType = ClosedGenericMatcher.ExtractGenericInterface(type, typeof(Task<>));
 
-            return genericType?.GenericTypeArguments[0];
+            Type UnwrapGenericType(Type type, Type queryType)
+            {
+                var genericType = ClosedGenericMatcher.ExtractGenericInterface(type, queryType);
+                return genericType?.GenericTypeArguments[0] ?? type;
+            }
         }
 
         private Type GetRuntimeReturnType(Type declaredReturnType)

diff --git a/test/Microsoft.AspNetCore.Mvc.ApiExplorer.Test/DefaultApiDescriptionProviderTest.cs b/test/Microsoft.AspNetCore.Mvc.ApiExplorer.Test/DefaultApiDescriptionProviderTest.cs
@@ -394,6 +394,42 @@ public void GetApiDescription_PopulatesResponseType_WithProduct()
             Assert.NotNull(responseType.ModelMetadata);
         }
 
+        [Theory]
+        [InlineData(nameof(ReturnsActionResultOfProduct))]
+        [InlineData(nameof(ReturnsTaskOfActionResultOfProduct))]
+        public void GetApiDescription_PopulatesResponseType_ForActionResultOfT(string methodName)
+        {
+            // Arrange
+            var action = CreateActionDescriptor(methodName);
+
+            // Act
+            var descriptions = GetApiDescriptions(action);
+
+            // Assert
+            var description = Assert.Single(descriptions);
+            var responseType = Assert.Single(description.SupportedResponseTypes);
+            Assert.Equal(typeof(Product), responseType.Type);
+            Assert.NotNull(responseType.ModelMetadata);
+        }
+
+        [Theory]
+        [InlineData(nameof(ReturnsActionResultOfSequenceOfProducts))]
+        [InlineData(nameof(ReturnsTaskOfActionResultOfSequenceOfProducts))]
+        public void GetApiDescription_PopulatesResponseType_ForActionResultOfSequenceOfT(string methodName)
+        {
+            // Arrange
+            var action = CreateActionDescriptor(methodName);
+
+            // Act
+            var descriptions = GetApiDescriptions(action);
+
+            // Assert
+            var description = Assert.Single(descriptions);
+            var responseType = Assert.Single(description.SupportedResponseTypes);
+            Assert.Equal(typeof(IEnumerable<Product>), responseType.Type);
+            Assert.NotNull(responseType.ModelMetadata);
+        }
+
         [Fact]
         public void GetApiDescription_PopulatesResponseType_WithTaskOfProduct()
         {
@@ -1478,6 +1514,14 @@ private Product ReturnsProduct()
             return null;
         }
 
+        private ActionResult<Product> ReturnsActionResultOfProduct() => null;
+
+        private ActionResult<IEnumerable<Product>> ReturnsActionResultOfSequenceOfProducts() => null;
+
+        private Task<ActionResult<Product>> ReturnsTaskOfActionResultOfProduct() => null;
+
+        private Task<ActionResult<IEnumerable<Product>>> ReturnsTaskOfActionResultOfSequenceOfProducts() => null;
+
         private void AcceptsProduct(Product product)
         {
         }