Media type application/problem+json still lost in combination with ProducesAttribute

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

This issue is the same as reported and resolved here: https://github.com/dotnet/aspnetcore/issues/19510

Having tested with the project that is the previous issue’s minimal repro (in .NET 6 instead of .NET core 3.1), I’ve found the same issue still persists.

That is, a controller with ProducesAttribute set to application/json will set the response header media-type to application/json when it’s returning a ProblemDetails or ValidationProblemDetails. It’s supposed to return application/problem+json.

Expected Behavior

When the controller or framework returns a ProblemDetails or ValidationProblemDetails, the response header media type should be application/problem+json as per https://datatracker.ietf.org/doc/html/rfc7807#section-3

Steps To Reproduce

Minimalistic repro project: https://github.com/dsun1/ProblemMediaTypeIssue

Attribute a controller class or method with ProducesAttribute("application/json"). If that controller returns a problem, or if the framework returns a validation problem, the response media type will be application/json instead of application/problem+json.

Exceptions (if any)

No response

.NET Version

6.0.101

Anything else?

dotnet --info

.NET SDK (reflecting any global.json):
 Version:   6.0.101
 Commit:    ef49f6213a

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  11.0
 OS Platform: Darwin
 RID:         osx.10.16-x64
 Base Path:   /usr/local/share/dotnet/sdk/6.0.101/

Host (useful for support):
  Version: 6.0.1
  Commit:  3a25a7f1cc

.NET SDKs installed:
  2.1.818 [/usr/local/share/dotnet/sdk]
  3.1.416 [/usr/local/share/dotnet/sdk]
  5.0.404 [/usr/local/share/dotnet/sdk]
  6.0.101 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.30 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.30 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.22 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.13 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.30 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.22 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.13 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.1 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

[agilenut]

One reason we use [Produces(“application/json”] is because we want our swagger documentation to show application/json for our normal content.

Same here. We need to be able to use both and get the correct media types.

[captainsafia]

❌ Test 4 - Problem() with [Produces(“application/problem+json”, “application/json”)]

So, the ProducesAttribute has an OnResultExecuting hook that runs before the logic in the ObjectResultExecutor that was modified in the referenced PR runs. This OnResultExecuting will clear out result.ContentTypes and replace it with the content types that are defined in the ProducesAttribute.

https://github.com/dotnet/aspnetcore/blob/b21596afeb7412844ee5e19f6e5bef832c533c0f/src/Mvc/Mvc.Core/src/ProducesAttribute.cs#L91

https://github.com/dotnet/aspnetcore/blob/b21596afeb7412844ee5e19f6e5bef832c533c0f/src/Mvc/Mvc.Core/src/ProducesAttribute.cs#L101-L108

So, this is going to set result.ContentTypes to ["application/problem+json", "application/json"]. Now the InferContentType method modified in the referenced PR effectively no-ops because result.ContentTypes is not empty and the result.Value is not ProblemDetails.

https://github.com/dotnet/aspnetcore/blob/main/src/Mvc/Mvc.Core/src/Infrastructure/ObjectResultExecutor.cs#L130-L142

I believe that the tests introduced in that PR didn’t catch the issue because they don’t account for the fact that the ProducesAttribute modifies the content types in this way.

I think the fundamental right choice here is to modify the ProducesAttribute such that the OnResultExecuting invocation no-ops under certain scenarios since that’s the root cause here.