According to C# specification:
The set of values that an enum type can take on is not limited by its enum members. In particular, any value of the underlying type of an enum can be cast to the enum type and is a distinct valid value of that enum type
Therefore you can cast status code 422 to HttpStatusCode.
Example controller:
using System.Net;
using System.Net.Http;
using System.Web.Http;
namespace CompanyName.Controllers.Api
{
[RoutePrefix("services/noop")]
[AllowAnonymous]
public class NoOpController : ApiController
{
[Route]
[HttpGet]
public IHttpActionResult GetNoop()
{
return new System.Web.Http.Results.ResponseMessageResult(
Request.CreateErrorResponse(
(HttpStatusCode)422,
new HttpError("Something goes wrong")
)
);
}
}
}