Missing charset=utf-8 in the produces definition

[xlegalles]

VERSION:

2.3.0 and ASP.NET Core 2.1

STEPS TO REPRODUCE:

We describe an API using attributes. For example

[HttpGet("{fieldId:guid}", Name = "FieldById")]
[ProducesResponseType(typeof(FieldDtoWithHierarchy), (int)HttpStatusCode.OK)]
public Task<IActionResult> GetField(Guid fieldId){...}

Which provides the typical result in the swagger.json file:

"produces": [
          "text/plain",
          "application/json",
          "text/json"
        ]

But there is no way to specify a response of type "application/json; charset=utf-8" which is btw exactly what a browser will receive from the previous method. So there is a slight difference between a real answer and the swagger description.

I've tried adding a [Produces("application/json;charset=utf-8")] at the controller level or at the method level but it does not change anything. I don't find any way to add the charset definition into the swagger file.

You may think that this is a detail but it is not when we test the API using PACT:

• if the swagger.json does not provide the charset, the PACT must do the same i.e. not expect the charset. This way, both are considered compatible. (We use swagger-mock-validator to do it)
• but as soon as we want to test the PACT against the API, we get into the problem that ASP.NET Core does expose an "application/json; charset=utf-8" header with a charset. And tests fail.

Thank you for your help

[Kiechlus]

Is there any news on this? This produces big problems on our side because the Openapi Generator v6 packages check the content type exactly:

• The openapi description generated by Swashbuckle claims content type is only application/json
• However, dotnet returns application/json; charset=utf-8
• Therefore, any calls with the v6 clients throw exceptions.ApiValueError: Invalid content_type returned. Content_type='application/json; charset=utf-8' was returned when only {'application/json'} are defined for status_code=201

Update We got our problem fixed by simply allowing both content types: [Produces(System.Net.Mime.MediaTypeNames.Application.Json, "application/json; charset=utf-8")]