Calling BadRequest in controller is inconsistent with attribute validation

Describe the bug

After upgrading to ASP.NET Core 2.2, I noticed that attribute-based model validation produces 400 response bodies like the following:

{
    "errors": {
        "Model.Field": [
            "error message"
        ]
    },
    "title": "One or more validation errors occurred.",
    "status": 400,
    "traceId": "|e43bcb39071100489dc1590f71370445.4fc1232b_"
}

I have some additional validation in my controller action based on a database lookup that looks something like this:

try
{
    this.service.ServiceCall(model);
}
catch (InvalidModelException e)
{
    this.ModelState.AddModelError(nameof(Model.Field), e.Message);
    return this.BadRequest(this.ModelState);
}

The resulting response body looks like this:

{
    "Model.Field": [
        "error message"
    ]
}

Expected behavior

I would expect that calling ModelState.AddModelError from a controller action, then passing ModelState to BadRequest would give a response body similar to that of attribute-based model validation.

Additional context

I noticed that calling

return this.BadRequest(new ValidationProblemDetails(this.ModelState));

gives a response body very close to the desired one, minus the traceId field.

[khellang]

@durgeshkumar14 There’s no out-of-the-box option to turn it off.

For regular client error mapping, you need to provide your own implementation of IClientErrorFactory. It’s probably best to just use the default as a starting point:

https://github.com/aspnet/AspNetCore/blob/09b50850bc428119ea5adfdbceb0470b7a5c2546/src/Mvc/src/Microsoft.AspNetCore.Mvc.Core/Infrastructure/ProblemDetailsClientErrorFactory.cs#L10-L53

And leave out the call to SetTraceId. Add it like this:

services.TryAddSingleton<IClientErrorFactory, MyCustomProblemDetailsClientErrorFactory>();

---

For validation errors, MVC uses the ApiBehaviorOptions.InvalidModelStateResponseFactory option to convert the validation errors into a result. The default implementation looks like this:

https://github.com/aspnet/AspNetCore/blob/708dc5cb5abd1fe0aa409f355b9e0cea8f6846d4/src/Mvc/src/Microsoft.AspNetCore.Mvc.Core/DependencyInjection/ApiBehaviorOptionsSetup.cs#L106-L121

You can set it by doing something like this:

services.Configure<ApiBehaviorOptions>(options =>
{
    options.InvalidModelStateResponseFactory = context =>
    {
        var problemDetails = new ValidationProblemDetails(context.ModelState);

        var result = new BadRequestObjectResult(problemDetails); 

        result.ContentTypes.Add("application/problem+json"); 
        result.ContentTypes.Add("application/problem+xml"); 
  
        return result;
    };
});

[khellang]

It’s part of the extension data. See ProblemDetailsClientErrorFactory.SetTraceId 😉