Select return content type based on Accept header

README.md

@@ -458,14 +458,14 @@ follows:
 builder.Services.AddResponseCompression(options =>
 {
     options.EnableForHttps = true; // may lead to CRIME and BREACH attacks
-    options.MimeTypes = new[] { "application/json", "application/graphql+json" };
+    options.MimeTypes = new[] { "application/json", "application/graphql-response+json" };
 })
 
 // place this first/early in the pipeline
 app.UseResponseCompression();
 ```
 
-In order to compress GraphQL responses, the `application/graphql+json` content type must be
+In order to compress GraphQL responses, the `application/graphql-response+json` content type must be
 added to the `MimeTypes` option.  You may choose to enable other content types as well.
 
 Please note that enabling response compression over HTTPS can lead to CRIME and BREACH
@@ -661,7 +661,7 @@ A list of methods are as follows:
 | `HandleWebSocketSubProtocolNotSupportedAsync` | Writes a '400 Invalid WebSocket sub-protocol.' message to the output. |
 
 Below is a sample of custom middleware to change the response content type to `application/json`,
-rather than the default of `application/graphql+json`:
+rather than the default of `application/graphql-response+json`:
 
 ```csharp
 class MyMiddleware<TSchema> : GraphQLHttpMiddleware<TSchema>

docs/migration/migration7.md

@@ -1,12 +1,12 @@
-# Migrating from v6 to v7
+# Migrating from v6 to v7.1
 
 ## Major changes and new features
 
 #### GraphQL Middleware
 
 - Configuration simplified to a single line of code
 - Single middleware to support GET, POST and WebSocket connections (configurable)
-- Media type of 'application/graphql+json' is accepted and returned as recommended by the draft spec (configurable via virtual method)
+- Media type of 'application/graphql-response+json' is accepted and returned as recommended by the draft spec (configurable via virtual method)
 - Batched requests will execute in parallel within separate service scopes (configurable)
 - Authorization rules can be set on endpoints, regardless of schema configuration
 - Mutation requests are disallowed over GET connections, as required by the spec

src/Transports.AspNetCore/GraphQLHttpMiddleware.cs

@@ -1,5 +1,7 @@
 #pragma warning disable CA1716 // Identifiers should not match keywords
 
+using Microsoft.AspNetCore.Http;
+
 namespace GraphQL.Server.Transports.AspNetCore;
 
 /// <inheritdoc/>
@@ -54,7 +56,9 @@ public class GraphQLHttpMiddleware : IUserContextBuilder
     private const string MEDIATYPE_GRAPHQLJSON = "application/graphql+json";
     private const string MEDIATYPE_JSON = "application/json";
     private const string MEDIATYPE_GRAPHQL = "application/graphql";
+    internal const string CONTENTTYPE_JSON = "application/json; charset=utf-8";
     internal const string CONTENTTYPE_GRAPHQLJSON = "application/graphql+json; charset=utf-8";
+    internal const string CONTENTTYPE_GRAPHQLRESPONSEJSON = "application/graphql-response+json; charset=utf-8";
 
     /// <summary>
     /// Initializes a new instance.
@@ -444,6 +448,16 @@ protected virtual async Task<ExecutionResult> ExecuteRequestAsync(HttpContext co
     ValueTask<IDictionary<string, object?>?> IUserContextBuilder.BuildUserContextAsync(HttpContext context, object? payload)
         => BuildUserContextAsync(context, payload);
 
+    private static readonly (string MediaType, string ResponseType)[] _validMediaTypes = new[]
+    {
+        ("application/graphql-response+json", CONTENTTYPE_GRAPHQLRESPONSEJSON),
+        ("application/json", CONTENTTYPE_JSON),
+        ("application/graphql+json", CONTENTTYPE_GRAPHQLJSON),
+        ("*/*", CONTENTTYPE_GRAPHQLRESPONSEJSON),
+        ("application/*", CONTENTTYPE_GRAPHQLRESPONSEJSON),
+        ("application/*+json", CONTENTTYPE_GRAPHQLRESPONSEJSON),
+    };
+
     /// <summary>
     /// Selects a response content type string based on the <see cref="HttpContext"/>.
     /// Defaults to <see cref="CONTENTTYPE_GRAPHQLJSON"/>.  Override this value for compatibility
@@ -454,7 +468,23 @@ protected virtual async Task<ExecutionResult> ExecuteRequestAsync(HttpContext co
     /// <see cref="WriteJsonResponseAsync{TResult}(HttpContext, HttpStatusCode, TResult)"/>.
     /// </summary>
     protected virtual string SelectResponseContentType(HttpContext context)
-        => CONTENTTYPE_GRAPHQLJSON;
+    {
+        var acceptHeaders = context.Request.GetTypedHeaders().Accept;
+        if (acceptHeaders != null)
+        {
+            for (int i = 0; i < acceptHeaders.Count; i++)
+            {
+                for (int j = 0; j < _validMediaTypes.Length; j++)
+                {
+                    var (mediaType, responseType) = _validMediaTypes[j];
+                    if (acceptHeaders[i].MediaType.Equals(mediaType, StringComparison.OrdinalIgnoreCase))
+                        return responseType;
+                }
+            }
+        }
+
+        return CONTENTTYPE_GRAPHQLRESPONSEJSON;
+    }
 
     /// <summary>
     /// Writes the specified object (usually a GraphQL response represented as an instance of <see cref="ExecutionResult"/>) as JSON to the HTTP response stream.

tests/Samples.Tests/TestServerExtensions.cs

@@ -54,7 +54,7 @@ public static async Task VerifyGraphQLPostAsync(
     {
         using var client = server.CreateClient();
         var body = System.Text.Json.JsonSerializer.Serialize(new { query });
-        var content = new StringContent(body, System.Text.Encoding.UTF8, "application/graphql+json");
+        var content = new StringContent(body, System.Text.Encoding.UTF8, "application/json");
         using var request = new HttpRequestMessage(HttpMethod.Post, url);
         request.Content = content;
         if (jwtToken != null)

tests/Transports.AspNetCore.Tests/Middleware/GetTests.cs

@@ -65,6 +65,29 @@ public async Task BasicTest()
         await response.ShouldBeAsync(@"{""data"":{""count"":0}}");
     }
 
+    [Theory]
+    [InlineData("application/graphql+json", "application/graphql+json; charset=utf-8")]
+    [InlineData("application/json", "application/json; charset=utf-8")]
+    [InlineData("application/json; charset=utf-8", "application/json; charset=utf-8")]
+    [InlineData("application/json; charset=UTF-8", "application/json; charset=utf-8")]
+    [InlineData("APPLICATION/JSON", "application/json; charset=utf-8")]
+    [InlineData("APPLICATION/JSON; CHARSET=\"UTF-8\" ", "application/json; charset=utf-8")]
+    [InlineData("*/*; CHARSET=\"UTF-8\" ", "application/graphql-response+json; charset=utf-8")]
+    [InlineData("application/*; charset=utf-8", "application/graphql-response+json; charset=utf-8")]
+    [InlineData("application/*+json; charset=utf-8", "application/graphql-response+json; charset=utf-8")]
+    [InlineData("application/pdf", "application/graphql-response+json; charset=utf-8")]
+    [InlineData("application/json; charset=utf-7", "application/json; charset=utf-8")]
+    public async Task AcceptHeaderHonored(string mediaType, string expected)
+    {
+        var client = _server.CreateClient();
+        using var request = new HttpRequestMessage(HttpMethod.Get, "/graphql?query={count}");
+        request.Headers.Add("Accept", mediaType);
+        using var response = await client.SendAsync(request);
+        var contentType = response.Content.Headers.ContentType?.ToString();
+        contentType.ShouldBe(expected);
+        (await response.Content.ReadAsStringAsync()).ShouldBe(@"{""data"":{""count"":0}}");
+    }
+
     [Fact]
     public async Task NoUseWebSockets()
     {

tests/Transports.AspNetCore.Tests/ShouldlyExtensions.cs

@@ -13,8 +13,10 @@ public static Task ShouldBeAsync(this HttpResponseMessage message, string expect
     public static async Task ShouldBeAsync(this HttpResponseMessage message, HttpStatusCode httpStatusCode, string expectedResponse)
     {
         message.StatusCode.ShouldBe(httpStatusCode);
-        message.Content.Headers.ContentType?.MediaType.ShouldBe("application/graphql+json");
-        message.Content.Headers.ContentType?.CharSet.ShouldBe("utf-8");
+        var contentType = message.Content.Headers.ContentType;
+        contentType.ShouldNotBeNull();
+        contentType.MediaType.ShouldBe("application/graphql-response+json");
+        contentType.CharSet.ShouldBe("utf-8");
         var actualResponse = await message.Content.ReadAsStringAsync();
         actualResponse.ShouldBe(expectedResponse);
     }

tests/Transports.AspNetCore.Tests/TestServerExtensions.cs

@@ -15,7 +15,7 @@ public static async Task<string> ExecutePost(this TestServer server, string url,
     {
         var client = server.CreateClient();
         var data = System.Text.Json.JsonSerializer.Serialize(new { query = query, variables = variables });
-        var content = new StringContent(data, Encoding.UTF8, "application/graphql+json");
+        var content = new StringContent(data, Encoding.UTF8, "application/json");
         using var response = await client.PostAsync(url, content);
         response.EnsureSuccessStatusCode();
         var str = await response.Content.ReadAsStringAsync();