Ensure UnsupportedContentTypeFilter runs before ModelStateInvalidFilter

Both UnsupportedContentTypeFilter and ModelStateInvalidFilter use ModelState to
determine the response. UnsupportedContentTypeFilter returns a more specific
response and should execute earlier than the latter filter.

Fixes #8236

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/UnsupportedContentTypeFilter.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.Infrastructure;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding
 {
@@ -10,8 +11,16 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
     /// <see cref="ActionContext.ModelState"/> and short-circuits the pipeline
     /// with an Unsupported Media Type (415) response.
     /// </summary>
-    public class UnsupportedContentTypeFilter : IActionFilter
+    public class UnsupportedContentTypeFilter : IActionFilter, IOrderedFilter
     {
+        /// <summary>
+        /// Gets or sets the filter order. <see cref="IOrderedFilter.Order"/>.
+        /// <para>
+        /// Defaults to <c>-3000</c> to ensure it executes before <see cref="ModelStateInvalidFilter"/>.
+        /// </para>
+        /// </summary>
+        public int Order { get; set; } = -3000;
+
         /// <inheritdoc />
         public void OnActionExecuting(ActionExecutingContext context)
         {
@@ -32,7 +41,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             foreach (var kvp in modelState)
             {
                 var errors = kvp.Value.Errors;
-                for (int i = 0; i < errors.Count; i++)
+                for (var i = 0; i < errors.Count; i++)
                 {
                     var error = errors[i];
                     if (error.Exception is UnsupportedContentTypeException)

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

@@ -5,6 +5,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Net;
 using System.Net.Http;
+using System.Text;
 using System.Threading.Tasks;
 using BasicWebSite.Models;
 using Newtonsoft.Json;
@@ -58,6 +59,38 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             );
         }
 
+        [Fact]
+        public async Task ActionsReturnUnsupportedMediaType_WhenMediaTypeIsNotSupported()
+        {
+            // Arrange
+            var requestMessage = new HttpRequestMessage(HttpMethod.Post, "/contact")
+            {
+                Content = new StringContent("some content", Encoding.UTF8, "text/css"),
+            };
+
+            // Act
+            var response = await Client.SendAsync(requestMessage);
+
+            // Assert
+            await response.AssertStatusCodeAsync(HttpStatusCode.UnsupportedMediaType);
+        }
+
+        [Fact]
+        public async Task ActionsReturnUnsupportedMediaType_WhenEncodingIsUnsupported()
+        {
+            // Arrange
+            var requestMessage = new HttpRequestMessage(HttpMethod.Post, "/contact")
+            {
+                Content = new StringContent("some content", Encoding.UTF7, "application/json"),
+            };
+
+            // Act
+            var response = await Client.SendAsync(requestMessage);
+
+            // Assert
+            await response.AssertStatusCodeAsync(HttpStatusCode.UnsupportedMediaType);
+        }
+
         [Fact]
         public async Task ActionsReturnBadRequest_UsesProblemDescriptionProviderAndApiConventionsToConfigureErrorResponse()
         {