ApiExplorer Support for HttpResults types for Controllers

src/Mvc/Mvc.Core/src/Routing/ActionEndpointFactory.cs

@@ -353,11 +353,13 @@ private static void AddActionDataToBuilder(
 
         // Add metadata inferred from the parameter and/or return type before action-specific metadata.
         // MethodInfo *should* never be null given a ControllerActionDescriptor, but this is unenforced.
+        var metadataCountBeforePopulating = builder.Metadata.Count;
         if (controllerActionDescriptor?.MethodInfo is not null)
         {
             EndpointMetadataPopulator.PopulateMetadata(controllerActionDescriptor.MethodInfo, builder);
         }
 
+        var metadataCountAfterPopulating = builder.Metadata.Count;
         // Add action-specific metadata early so it has a low precedence
         if (action.EndpointMetadata != null)
         {
@@ -369,6 +371,29 @@ private static void AddActionDataToBuilder(
 
         builder.Metadata.Add(action);
 
+        if (metadataCountAfterPopulating != metadataCountBeforePopulating)
+        {
+            action.EndpointMetadata ??= [];
+            HashSet<int> producesResponseMetadataByAttribute = [];
+            foreach (var endpointMetadataInAttributes in action.EndpointMetadata)
+            {
+                if (endpointMetadataInAttributes is IProducesResponseTypeMetadata metadataInAttributes
+                   && !producesResponseMetadataByAttribute.Contains(metadataInAttributes.StatusCode))
+                {
+                    producesResponseMetadataByAttribute.Add(metadataInAttributes.StatusCode);
+                }
+            }
+
+            foreach (var endpointMetadata in builder.Metadata)
+            {
+                if (endpointMetadata is IProducesResponseTypeMetadata metadata
+                   && !producesResponseMetadataByAttribute.Contains(metadata.StatusCode))
+                {
+                    action.EndpointMetadata.Add(metadata);
+                }
+            }
+        }
+
         // MVC guarantees that when two of it's endpoints have the same route name they are equivalent.
         //
         // The case for this looks like:

src/Mvc/test/Mvc.FunctionalTests/ApiExplorerTest.cs

@@ -3,13 +3,12 @@
 
 using System.Net;
 using System.Net.Http;
+using System.Reflection;
 using ApiExplorerWebSite;
+using Microsoft.AspNetCore.InternalTesting;
 using Microsoft.AspNetCore.Mvc.Formatters;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
-using Microsoft.AspNetCore.InternalTesting;
 using Newtonsoft.Json;
-using Microsoft.Extensions.Logging;
-using System.Reflection;
 using Xunit.Abstractions;
 
 namespace Microsoft.AspNetCore.Mvc.FunctionalTests;
@@ -1565,6 +1564,84 @@ public async Task ApiExplorer_LogsInvokedDescriptionProvidersOnStartup()
         Assert.Contains(TestSink.Writes, w => w.Message.Equals("Executing API description provider 'JsonPatchOperationsArrayProvider' from assembly Microsoft.AspNetCore.Mvc.NewtonsoftJson v42.42.42.42.", StringComparison.Ordinal));
     }
 
+    [Fact]
+    public async Task ApiExplorer_SupportsIResults()
+    {
+        // Act
+        var response = await Client.GetAsync($"http://localhost/ApiExplorerHttpResultsController/GetOfT");
+        var responseBody = await response.EnsureSuccessStatusCode().Content.ReadAsStringAsync();
+        var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(responseBody);
+
+        //Assert
+        var description = Assert.Single(result);
+        Assert.Collection(
+           description.SupportedResponseTypes.OrderBy(r => r.StatusCode),
+           responseType =>
+           {
+               Assert.Equal(typeof(int).FullName, responseType.ResponseType);
+               Assert.Equal(200, responseType.StatusCode);
+               Assert.False(responseType.IsDefaultResponse);
+           },
+            responseType =>
+            {
+                Assert.Equal(typeof(DateTime).FullName, responseType.ResponseType);
+                Assert.Equal(404, responseType.StatusCode);
+                Assert.False(responseType.IsDefaultResponse);
+            });
+    }
+
+    [Fact]
+    public async Task ApiExplorer_SupportsIResultsWhenNoType()
+    {
+        // Act
+        var response = await Client.GetAsync($"http://localhost/ApiExplorerHttpResultsController/GetWithNotFoundWithNoType");
+        var responseBody = await response.EnsureSuccessStatusCode().Content.ReadAsStringAsync();
+        var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(responseBody);
+
+        //Assert
+        var description = Assert.Single(result);
+        Assert.Collection(
+           description.SupportedResponseTypes.OrderBy(r => r.StatusCode),
+           responseType =>
+           {
+               Assert.Equal(typeof(int).FullName, responseType.ResponseType);
+               Assert.Equal(200, responseType.StatusCode);
+               Assert.False(responseType.IsDefaultResponse);
+           },
+            responseType =>
+            {
+                Assert.Equal(typeof(void).FullName, responseType.ResponseType);
+                Assert.Equal(404, responseType.StatusCode);
+                Assert.False(responseType.IsDefaultResponse);
+            });
+    }
+
+    [Fact]
+    public async Task ApiExplorer_SupportsIResultsWhenDifferentProduceType()
+    {
+        // Act
+        var response = await Client.GetAsync($"http://localhost/ApiExplorerHttpResultsController/GetWithDifferentProduceType");
+        var responseBody = await response.EnsureSuccessStatusCode().Content.ReadAsStringAsync();
+        var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(responseBody);
+
+        //Assert
+        var description = Assert.Single(result);
+        Assert.Collection(
+           description.SupportedResponseTypes.OrderBy(r => r.StatusCode),
+           responseType =>
+           {
+               Assert.Equal(typeof(long).FullName, responseType.ResponseType);
+               Assert.Equal(200, responseType.StatusCode);
+               Assert.False(responseType.IsDefaultResponse);
+           },
+            responseType =>
+            {
+                Assert.Equal(typeof(void).FullName, responseType.ResponseType);
+                Assert.Equal(404, responseType.StatusCode);
+                Assert.False(responseType.IsDefaultResponse);
+            });
+    }
+
     private IEnumerable<string> GetSortedMediaTypes(ApiExplorerResponseType apiResponseType)
     {
         return apiResponseType.ResponseFormats

src/Mvc/test/WebSites/ApiExplorerWebSite/ApiExplorerWebSite.csproj

@@ -8,7 +8,7 @@
     <Reference Include="Microsoft.AspNetCore.Mvc" />
     <Reference Include="Microsoft.AspNetCore.Mvc.Formatters.Xml" />
     <Reference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" />
-
+    <Reference Include="Microsoft.AspNetCore.Http.Results" />
     <Reference Include="Microsoft.AspNetCore.Server.IISIntegration" />
     <Reference Include="Microsoft.AspNetCore.Server.Kestrel" />
     <Reference Include="Microsoft.AspNetCore.StaticFiles" />

src/Mvc/test/WebSites/ApiExplorerWebSite/Controllers/ApiExplorerHttpResultsController.cs

@@ -0,0 +1,36 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ApiExplorerWebSite.Controllers;
+
+public class ApiExplorerHttpResultsController : Controller
+{
+    [HttpGet("ApiExplorerHttpResultsController/GetOfT")]
+    public Results<Ok<int>, NotFound<DateTime>> Get()
+    {
+        return Random.Shared.Next() % 2 == 0
+            ? TypedResults.Ok(0)
+            : TypedResults.NotFound(DateTime.Now);
+    }
+
+    [HttpGet("ApiExplorerHttpResultsController/GetWithNotFoundWithNoType")]
+    public async Task<Results<Ok<int>, NotFound>> GetWithNotFoundWithNoType()
+    {
+        await Task.Delay(1);
+        return Random.Shared.Next() % 2 == 0
+            ? TypedResults.Ok(0)
+            : TypedResults.NotFound();
+    }
+    [ProducesResponseType(200, Type = typeof(long))]
+    [HttpGet("ApiExplorerHttpResultsController/GetWithDifferentProduceType")]
+    public async Task<Results<Ok<int>, NotFound>> GetWithDifferentProduceType()
+    {
+        await Task.Delay(1);
+        return Random.Shared.Next() % 2 == 0
+            ? TypedResults.Ok(0)
+            : TypedResults.NotFound();
+    }
+}

src/OpenApi/sample/Controllers/TestController.cs

@@ -3,6 +3,7 @@
 
 using System.ComponentModel.DataAnnotations;
 using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Http.HttpResults;
 using Microsoft.AspNetCore.Mvc;
 
 [ApiController]
@@ -17,6 +18,15 @@ public string GetByIdAndName(RouteParamsContainer paramsContainer)
         return paramsContainer.Id + "_" + paramsContainer.Name;
     }
 
+    [HttpGet]
+    [Route("/getbyidandnameWithIResults/{id}/{name}")]
+    public Results<Ok<string>, NotFound> GetByIdAndNameWithIResults(RouteParamsContainer paramsContainer)
+    {
+        return Random.Shared.Next() % 2 == 0 ?
+            TypedResults.Ok(paramsContainer.Id + "_" + paramsContainer.Name)
+            : TypedResults.NotFound();
+    }
+
     [HttpPost]
     [Route("/forms")]
     public IActionResult PostForm([FromForm] MvcTodo todo)

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=controllers.verified.txt

@@ -54,6 +54,49 @@
         }
       }
     },
+    "/getbyidandnameWithIResults/{id}/{name}": {
+      "get": {
+        "tags": [
+          "Test"
+        ],
+        "parameters": [
+          {
+            "name": "Id",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "integer",
+              "format": "int32"
+            }
+          },
+          {
+            "name": "Name",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "minLength": 5,
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "minLength": 5,
+                  "type": "string"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "Not Found"
+          }
+        }
+      }
+    },
     "/forms": {
       "post": {
         "tags": [