Make it easier to return Problem Details responses for server errors

[DamianEdwards]

Add a set of new Problem helper methods on ControllerBase, that populates a ProblemDetails type with relevant values for simple returning of errors through the MVC response pipeline, e.g.:

private ObjectResult Problem()
{
    return Problem(detail: null);
}
 
private ObjectResult Problem(string detail)
{
    var problemDetails = new ProblemDetails
    {
        Title = "An error occurred while processing your request.",
        Detail = detail,
        Status = 500
    };
 
    problemDetails.Extensions.Add("traceId", Activity.Current?.Id ?? HttpContext.TraceIdentifier);
    return Problem(problemDetails);
}
 
private ObjectResult Problem(ProblemDetails problemDetails)
{
    return new ObjectResult(problemDetails) { StatusCode = problemDetails.Status };
}

@rynowak

[thomaslevesque]

I was looking for something like this today.

Currently, there's no convenient way to return a problem details response with the ability to specify the title/detail/instance/etc. Methods like NotFound(), BadRequest(), etc produce a ProblemDetails with a default title and no detail.

A Problem() method would indeed be very useful. I think an overload that accepts the status code would be useful too, since you might want to return problem details for errors other than 500.

---

Suggestion: also create a ProblemDetailsResult class, which could handle things like:

• adding a traceId
• setting appropriate content types ("application/problem+json" and "application/problem+xml")
• setting title and type to default values if they're not set

All these things are currently done in the default InvalidModelStateResponseFactory and in ProblemDetailsClientErrorFactory

---

[thomaslevesque]

BTW, I'm interested in implementing this, if there isn't someone already working on it.

[khellang]

• setting appropriate content types ("application/problem+json" and "application/problem+xml")

This is already done for you, if you use an ObjectResult:

https://github.com/aspnet/AspNetCore/blob/5ca92305c2e6452e2add9a2eb115963896c6fe85/src/Mvc/Mvc.Core/src/Infrastructure/ObjectResultExecutor.cs#L135-L139

[thomaslevesque]

Oh, nice! Thanks @khellang