Suppress default status code response type in api descriptions when explicit response types have been provided

[Fixes #4823] How to override the default (200) status code with ProducesResponseType

src/Microsoft.AspNetCore.Mvc.ApiExplorer/DefaultApiDescriptionProvider.cs

@@ -358,13 +358,6 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
             // Build list of all possible return types (and status codes) for an action.
             var objectTypes = new Dictionary<int, Type>();
 
-            if (type != null && type != typeof(void))
-            {
-                // This return type can be overriden by any response metadata
-                // attributes later if the user wishes to.
-                objectTypes[StatusCodes.Status200OK] = type;
-            }
-
             // Get the content type that the action explicitly set to support.
             // Walk through all 'filter' attributes in order, and allow each one to see or override
             // the results of the previous ones. This is similar to the execution path for content-negotiation.
@@ -382,6 +375,14 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
                 }
             }
 
+            // Set the default status only when no status has already been set explicitly
+            if (objectTypes.Count == 0
+                && type != null
+                && type != typeof(void))
+            {
+                objectTypes[StatusCodes.Status200OK] = type;
+            }
+
             if (contentTypes.Count == 0)
             {
                 contentTypes.Add((string)null);

test/Microsoft.AspNetCore.Mvc.FunctionalTests/ApiExplorerTest.cs

@@ -523,6 +523,133 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             Assert.Equal("application/json", responseFormat.MediaType);
         }
 
+        [Fact]
+        public async Task ExplicitResponseTypeDecoration_SuppressesDefaultStatus()
+        {
+            // Arrange
+            var type1 = typeof(ApiExplorerWebSite.Product).FullName;
+            var type2 = typeof(ModelStateDictionary).FullName;
+            var expectedMediaTypes = new[] { "application/json", "text/json", "application/xml", "text/xml" };
+
+            // Act
+            var response = await Client.GetAsync(
+                "http://localhost/ApiExplorerResponseTypeWithAttribute/CreateProductWithDefaultResponseContentTypes");
+
+            var body = await response.Content.ReadAsStringAsync();
+            var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(body);
+
+            // Assert
+            var description = Assert.Single(result);
+            Assert.Equal(2, description.SupportedResponseTypes.Count);
+            var responseType = description.SupportedResponseTypes[0];
+            Assert.Equal(type1, responseType.ResponseType);
+            Assert.Equal(201, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+            responseType = description.SupportedResponseTypes[1];
+            Assert.Equal(type2, responseType.ResponseType);
+            Assert.Equal(400, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+        }
+
+        [Fact]
+        public async Task ExplicitResponseTypeDecoration_SuppressesDefaultStatus_AlsoHonorsProducesContentTypes()
+        {
+            // Arrange
+            var type1 = typeof(ApiExplorerWebSite.Product).FullName;
+            var type2 = typeof(ModelStateDictionary).FullName;
+            var expectedMediaTypes = new[] { "text/xml" };
+
+            // Act
+            var response = await Client.GetAsync(
+                "http://localhost/ApiExplorerResponseTypeWithAttribute/CreateProductWithLimitedResponseContentTypes");
+
+            var body = await response.Content.ReadAsStringAsync();
+            var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(body);
+
+            // Assert
+            var description = Assert.Single(result);
+            Assert.Equal(2, description.SupportedResponseTypes.Count);
+            var responseType = description.SupportedResponseTypes[0];
+            Assert.Equal(type1, responseType.ResponseType);
+            Assert.Equal(201, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+            responseType = description.SupportedResponseTypes[1];
+            Assert.Equal(type2, responseType.ResponseType);
+            Assert.Equal(400, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+        }
+
+        [Fact]
+        public async Task ExplicitResponseTypeDecoration_WithExplicitDefaultStatus()
+        {
+            // Arrange
+            var type1 = typeof(ApiExplorerWebSite.Product).FullName;
+            var type2 = typeof(ModelStateDictionary).FullName;
+            var expectedMediaTypes = new[] { "application/json", "text/json", "application/xml", "text/xml" };
+
+            // Act
+            var response = await Client.GetAsync(
+                "http://localhost/ApiExplorerResponseTypeWithAttribute/UpdateProductWithDefaultResponseContentTypes");
+
+            var body = await response.Content.ReadAsStringAsync();
+            var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(body);
+
+            // Assert
+            var description = Assert.Single(result);
+            Assert.Equal(2, description.SupportedResponseTypes.Count);
+            var responseType = description.SupportedResponseTypes[0];
+            Assert.Equal(type1, responseType.ResponseType);
+            Assert.Equal(200, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+            responseType = description.SupportedResponseTypes[1];
+            Assert.Equal(type2, responseType.ResponseType);
+            Assert.Equal(400, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+        }
+
+        [Fact]
+        public async Task ExplicitResponseTypeDecoration_WithExplicitDefaultStatus_SpecifiedViaProducesAttribute()
+        {
+            // Arrange
+            var type1 = typeof(ApiExplorerWebSite.Product).FullName;
+            var type2 = typeof(ModelStateDictionary).FullName;
+            var expectedMediaTypes = new[] { "text/xml" };
+
+            // Act
+            var response = await Client.GetAsync(
+                "http://localhost/ApiExplorerResponseTypeWithAttribute/UpdateProductWithLimitedResponseContentTypes");
+
+            var body = await response.Content.ReadAsStringAsync();
+            var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(body);
+
+            // Assert
+            var description = Assert.Single(result);
+            Assert.Equal(2, description.SupportedResponseTypes.Count);
+            var responseType = description.SupportedResponseTypes[0];
+            Assert.Equal(type1, responseType.ResponseType);
+            Assert.Equal(200, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+            responseType = description.SupportedResponseTypes[1];
+            Assert.Equal(type2, responseType.ResponseType);
+            Assert.Equal(400, responseType.StatusCode);
+            Assert.Equal(
+                expectedMediaTypes,
+                responseType.ResponseFormats.Select(responseFormat => responseFormat.MediaType).ToArray());
+        }
         [Fact]
         public async Task ApiExplorer_ResponseType_InheritingFromController()
         {

test/WebSites/ApiExplorerWebSite/Controllers/ApiExplorerResponseTypeWithAttributeController.cs

@@ -3,10 +3,11 @@
 
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
 
 namespace ApiExplorerWebSite
 {
-    [Route("ApiExplorerResponseTypeWithAttribute/[Action]")]
+    [Route("[controller]/[Action]")]
     public class ApiExplorerResponseTypeWithAttributeController : Controller
     {
         [HttpGet]
@@ -42,5 +43,34 @@ namespace ApiExplorerWebSite
         {
             return null;
         }
+
+        [ProducesResponseType(typeof(Product), 201)]
+        [ProducesResponseType(typeof(ModelStateDictionary), 400)]
+        public Product CreateProductWithDefaultResponseContentTypes(Product product)
+        {
+            return null;
+        }
+
+        [Produces("text/xml")] // Has status code as 200 but is not applied as it does not set 'Type'
+        [ProducesResponseType(typeof(Product), 201)]
+        [ProducesResponseType(typeof(ModelStateDictionary), 400)]
+        public Product CreateProductWithLimitedResponseContentTypes(Product product)
+        {
+            return null;
+        }
+
+        [ProducesResponseType(typeof(Product), 200)]
+        [ProducesResponseType(typeof(ModelStateDictionary), 400)]
+        public Product UpdateProductWithDefaultResponseContentTypes(Product product)
+        {
+            return null;
+        }
+
+        [Produces("text/xml", Type = typeof(Product))] // Has status code as 200
+        [ProducesResponseType(typeof(ModelStateDictionary), 400)]
+        public Product UpdateProductWithLimitedResponseContentTypes(Product product)
+        {
+            return null;
+        }
     }
 }