MVC: Correct metadata type for formdata enum parameters (dotnet#61399)

Author: ascott18

src/Mvc/Mvc.ApiExplorer/src/EndpointModelMetadata.cs

@@ -65,6 +65,7 @@ public static Type GetDisplayType(Type type)
             || underlyingType == typeof(TimeSpan)
             || underlyingType == typeof(decimal)
             || underlyingType == typeof(Guid)
-            || underlyingType == typeof(Uri) ? type : typeof(string);
+            || underlyingType == typeof(Uri)
+            || underlyingType.IsEnum ? type : typeof(string);
     }
 }

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiDocumentServiceTestsBase.cs

@@ -15,6 +15,7 @@
 using Microsoft.AspNetCore.Mvc.Formatters;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.OpenApi;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.Constraints;
@@ -234,8 +235,13 @@ public ControllerActionDescriptor CreateActionDescriptor(string methodName = nul
         };
         action.RouteValues.Add("controller", "Test");
         action.RouteValues.Add("action", action.MethodInfo.Name);
-        action.ActionConstraints = [new HttpMethodActionConstraint(["GET"])];
         action.EndpointMetadata = [..action.MethodInfo.GetCustomAttributes()];
+        action.ActionConstraints = [new HttpMethodActionConstraint(action
+            .EndpointMetadata
+            .OfType<IActionHttpMethodProvider>()
+            .SelectMany(a => a.HttpMethods)
+            .DefaultIfEmpty("GET")
+        )];
         if (controllerType is not null)
         {
             foreach (var attribute in controllerType.GetCustomAttributes())

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiSchemaService/OpenApiSchemaService.RequestBodySchemas.cs

@@ -708,4 +708,51 @@ public class Parent
         public IDictionary<string, Parent> SelfReferenceDictionary { get; set; } = new Dictionary<string, Parent>();
     }
 
+    /// <remarks>
+    /// Regression test for https://github.com/dotnet/aspnetcore/issues/61327
+    /// </remarks>
+    [Fact]
+    public async Task RespectsEnumDefaultValueInControllerFormParameters()
+    {
+        // Arrange
+        var actionDescriptor = CreateActionDescriptor(nameof(TestBodyController.FormPostWithOptionalEnumParam), typeof(TestBodyController));
+
+        // Assert
+        await VerifyOpenApiDocument(actionDescriptor, VerifyOptionalEnum);
+    }
+
+    [Fact]
+    public async Task RespectsEnumDefaultValueInMinimalApiFormParameters()
+    {
+        // Arrange
+        var builder = CreateBuilder();
+
+        // Act
+        builder.MapPost("/optionalEnum", ([FromForm(Name = "status")] Status status = Status.Approved) => { });
+
+        // Assert
+        await VerifyOpenApiDocument(builder, VerifyOptionalEnum);
+    }
+
+    private void VerifyOptionalEnum(OpenApiDocument document)
+    {
+        var operation = document.Paths["/optionalEnum"].Operations[HttpMethod.Post];
+        var properties = operation.RequestBody.Content["application/x-www-form-urlencoded"].Schema.Properties;
+        var property = properties["status"];
+
+        Assert.NotNull(property);
+        Assert.Equal(3, property.Enum.Count);
+        Assert.Equal("Approved", property.Default.GetValue<string>());
+    }
+
+    [ApiController]
+    [Produces("application/json")]
+    public class TestBodyController
+    {
+        [Route("/optionalEnum")]
+        [HttpPost]
+        internal Status FormPostWithOptionalEnumParam(
+            [FromForm(Name = "status")] Status status = Status.Approved
+        ) => status;
+    }
 }