API Analyzer doesn't recognize ControllerBase.ValidationProblem.

Describe the bug

The Web API Analyzer doesn't recognize ControllerBase.ValidationProblem() and does not prompt a codefix to add a [ProducesResponseType] attribute like it does for ControllerBase.BadRequest().

To Reproduce

Steps to reproduce the behavior:

1. Using ASP.NET Core 2.2
2. Install Microsoft.AspNetCore.Mvc.Api.Analyzers 2.2.0
3. Add return ValidationProblem(); to a controller marked with [ApiController].

Expected behavior

Analyzer catches the issue and underlines return ValidationProblem();
Codefix prompt to add appropriate attributes to action.

Additional context

Using ASP.NET Core 2.2 and Microsoft.AspNetCore.Mvc.Api.Analyzers 2.2.0. Since the default ModelStateInvalidFilter uses ValidationProblemDetails to build a 400 response object, it makes sense that people may want to do the same for validation problems within actions so that the response format is consistent in both cases. Alternatively or additionally, there should be a way to opt into ControllerBase.BadRequest(ModelState) using ValidationProblemDetails to build its response object for consistency with ModelStateInvalidFilter.

[mkArtakMSFT]

Thanks for contacting us, @webwizgordon.
@pranavkm, can you please look into this? Thanks!

[khellang]

ApiControllerBase, is that a custom base class in your app? Sounds like the same issue as #4410?

Sorry, that was a typo. It should be ControllerBase i.e. the built-in base class for API controllers. I've updated the original comment.

[khellang]

Ah, I see. That's probably because it returns ActionResult instead of a more specific result type, like BadRequestObjectResult, which has been annotated with a DefaultStatusCodeAttribute:

https://github.com/aspnet/AspNetCore/blob/74f1ccad0d25fb85d318cf9da5837d15648b36e2/src/Mvc/src/Microsoft.AspNetCore.Mvc.Core/ControllerBase.cs#L1833-L1846

https://github.com/aspnet/AspNetCore/blob/74f1ccad0d25fb85d318cf9da5837d15648b36e2/src/Mvc/src/Microsoft.AspNetCore.Mvc.Core/BadRequestObjectResult.cs#L11-L15

Is it intentional that ValidationProblem returns ActionResult instead of a more specific result type? Every other method in ControllerBase returns a specific result type.

[khellang]

Is it intentional that ValidationProblem returns ActionResult instead of a more specific result type?

I'm not sure. I tried to find the PR adding the method to see whether it had been discussed. @pranavkm probably knows.

I'm guessing it might be because some people like to use 422 instead of 400, so you could override the method and return a different result.

[pranavkm]

I'm guessing it might be because some people like to use 422 instead of 400, so you could override the method and return a different result.

Yes, that was the intent.

There are other issues, such as #4950, where the analyzer could infer the status code of an ActionResult returning method by diving into the method call, at least in fairly simple scenarios. Perhaps that would be the fix here.