ASP.NET Core Consistent JSON Problem Details Response

ASP.NET Core's default template adds RFC7807 Problem Details response to everything that results in 400: Bad Response:

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "traceId": "00-3b3e118eb02dac41bcfc5d7c93509896-daaf187e081ea94e-00",
  "errors": {
    "Foo": [
      "The Foo field is required."
    ]
  }
}

(note that the field is Pascal cased, whereas JSON is usually camel-cased).

Other response statuses return an empty body. Wouldn't it be nice to receive a nice JSON response, regardless the HTTP status (ie 403, 404, 500 etc)?

Lucikly ASP.NET Core has a lot of extension points so this can be fixed relatively easily. You can write a custom middleware to catch all non-successful status codes and return a Problem Details response.

I've created a small NuGet package to configure the API for you: https://github.com/ProblemDetails/Problem.Details

After going through the installation and configuration process, all the non-successful HTTP responses should result in a nice and consistent JSON responses:

404 Not Found

{
  "type": "https://httpstatuses.com/404",
  "title": "Error: Not Found",
  "status": 404
}

500 Internal Server Error

{
  "type": "https://httpstatuses.com/500",
  "title": "Error: Internal Server Error",
  "status": 500,
  "exception": "System.Exception: Testing 500\n   at Sample.WebApi.Controllers.WeatherForecastController.Get(Int32 id) in /Users/hanneskarask/dev/Problem.Details/samples/Sample.WebApi/Controllers/WeatherForecastController.cs:line 42\n   at lambda_method3(Closure , Object , Object[] )..."
}

(exception field can be toggled programmatically, i.e. shown only locally)

400 Bad Request

{
  "errors": {
    "foo": ["The foo field is required."]
  },
  "type": "https://httpstatuses.com/400",
  "title": "Error: Bad Request",
  "status": 400
}

(fields are now camel-cased)

Currently there are a few configuration options:

• You can override the titles

.MapStatusToTitle(HttpStatusCode.BadRequest, "One or more validation errors occurred")

• Map custom exceptions

.MapException<NotFoundException>(HttpStatusCode.NotFound)