there is zero benefit to using a different content type for errors

Author: thefringeninja

src/SqlStreamStore.HAL.Tests/MiddlewareFixture.cs

@@ -36,7 +36,10 @@ private MiddlewareFixture(OwinHttpMessageHandler messageHandler)
             HttpClient = new HttpClient(_messageHandler)
             {
                 BaseAddress = new UriBuilder().Uri,
-                DefaultRequestHeaders = { Accept = { new MediaTypeWithQualityHeaderValue("application/hal+json") } }
+                DefaultRequestHeaders =
+                {
+                    Accept = { new MediaTypeWithQualityHeaderValue(Constants.Headers.ContentTypes.HalJson) }
+                }
             };
         }
         public HttpClient HttpClient { get; }

src/SqlStreamStore.HAL.Tests/StreamAppendTests.cs

@@ -185,7 +185,7 @@ public async Task wrong_expected_version(int[] expectedVersions)
             {
                 response.StatusCode.ShouldBe(HttpStatusCode.Conflict);
                 response.Content.Headers.ContentType.ShouldBe(new MediaTypeHeaderValue(
-                    Constants.Headers.ContentTypes.ProblemDetails));
+                    Constants.Headers.ContentTypes.HalJson));
             }
             var page = await _fixture.StreamStore.ReadStreamForwards(StreamId, 0, int.MaxValue);
 

src/SqlStreamStore.HAL.Tests/StreamDeleteTests.cs

@@ -57,7 +57,7 @@ public async Task wrong_expected_version(int expectedVersion)
             {
                 response.StatusCode.ShouldBe(HttpStatusCode.Conflict);
                 response.Content.Headers.ContentType.ShouldBe(new MediaTypeHeaderValue(
-                    Constants.Headers.ContentTypes.ProblemDetails));
+                    Constants.Headers.ContentTypes.HalJson));
             }
 
             var page = await _fixture.StreamStore.ReadStreamForwards(StreamId, 0, 1);

src/SqlStreamStore.HAL/AppendStreamMiddleware.cs

@@ -44,7 +44,7 @@ private static MidFunc AppendStream(StreamResource stream) => next => async env
             }
             catch(WrongExpectedVersionException ex)
             {
-                await context.WriteProblemDetailsResponse(ex);
+                await context.WriteWrongExpectedVersion(ex);
             }
         };
     }

src/SqlStreamStore.HAL/Constants.cs

@@ -12,8 +12,8 @@ public static class Headers
 
             public static class ContentTypes
             {
-                public const string ProblemDetails = "application/problem+json";
                 public const string Json = "application/json";
+                public const string HalJson = "application/hal+json";
             }
         }
 

src/SqlStreamStore.HAL/DeleteStreamMiddleware.cs

@@ -45,7 +45,7 @@ private static MidFunc DeleteStream(StreamResource stream) => next => async env
             }
             catch(WrongExpectedVersionException ex)
             {
-                await context.WriteProblemDetailsResponse(ex);
+                await context.WriteWrongExpectedVersion(ex);
             }
         };
     }

src/SqlStreamStore.HAL/ExceptionExtensions.cs

@@ -2,6 +2,7 @@ namespace SqlStreamStore.HAL
 {
     using System.IO;
     using System.Threading.Tasks;
+    using Halcyon.HAL;
     using Microsoft.IO;
     using Microsoft.Owin;
     using Newtonsoft.Json;
@@ -15,7 +16,7 @@ private static readonly RecyclableMemoryStreamManager s_StreamManager
 
         public static async Task WriteHalResponse(this IOwinContext context, Response response)
         {
-            context.Response.ContentType = "application/hal+json";
+            context.Response.ContentType = Constants.Headers.ContentTypes.HalJson;
 
             context.Response.StatusCode = response.StatusCode;
 
@@ -45,13 +46,13 @@ public static async Task WriteHalResponse(this IOwinContext context, Response re
             }
         }
 
-        public static Task WriteProblemDetailsResponse(this IOwinContext context, WrongExpectedVersionException ex)
-        {
-            context.Response.StatusCode = 409;
-            context.Response.ContentType = Constants.Headers.ContentTypes.ProblemDetails;
-
-            return context.Response.WriteAsync(ex.ConvertToProblemDetails(), context.Request.CallCancelled);
-        }
+        public static Task WriteWrongExpectedVersion(this IOwinContext context, WrongExpectedVersionException ex)
+            => context.WriteHalResponse(new Response(new HALResponse(new
+            {
+                type = "WrongExpectedVersion",
+                title = "Wrong expected version.",
+                detail = ex.Message
+            }), 409));
 
         public static bool IsGetOrHead(this IOwinContext context)
             => context.Request.Method == "GET" || context.Request.Method == "HEAD";