Return JSON with error status code MVC

Question

I was trying to return an error to the call to the controller as advised in This link so that client can take appropriate action. The controller is called by javascript via

Answer 1

I was running Asp.Net Web Api 5.2.7 and it looks like the JsonResult class has changed to use generics and an asynchronous execute method. I ended up altering Richard Garside's solution:

public class JsonHttpStatusResult : JsonResult
{
    private readonly HttpStatusCode _httpStatus;

    public JsonHttpStatusResult(T content, JsonSerializerSettings serializer, Encoding encoding, ApiController controller, HttpStatusCode httpStatus) 
    : base(content, serializer, encoding, controller)
    {
        _httpStatus = httpStatus;
    }

    public override Task ExecuteAsync(CancellationToken cancellationToken)
    {
        var returnTask = base.ExecuteAsync(cancellationToken);
        returnTask.Result.StatusCode = HttpStatusCode.BadRequest;
        return returnTask;
    }
}

Following Richard's example, you could then use this class like this:

if(thereWereErrors)
{
    var errorModel = new CustomErrorModel("There was an error");
    return new JsonHttpStatusResult(errorModel, new JsonSerializerSettings(), new UTF8Encoding(), this, HttpStatusCode.InternalServerError);
}

Unfortunately, you can't use an anonymous type for the content, as you need to pass a concrete type (ex: CustomErrorType) to the JsonHttpStatusResult initializer. If you want to use anonymous types, or you just want to be really slick, you can build on this solution by subclassing ApiController to add an HttpStatusCode param to the Json methods :)

public abstract class MyApiController : ApiController
{
    protected internal virtual JsonHttpStatusResult Json(T content, HttpStatusCode httpStatus, JsonSerializerSettings serializerSettings, Encoding encoding)
    {
        return new JsonHttpStatusResult(content, httpStatus, serializerSettings, encoding, this);
    }

    protected internal JsonHttpStatusResult Json(T content, HttpStatusCode httpStatus, JsonSerializerSettings serializerSettings)
    {
        return Json(content, httpStatus, serializerSettings, new UTF8Encoding());
    }

    protected internal JsonHttpStatusResult Json(T content, HttpStatusCode httpStatus)
    {
        return Json(content, httpStatus, new JsonSerializerSettings());
    }
}

Then you can use it with an anonymous type like this:

if(thereWereErrors)
{
    var errorModel = new { error = "There was an error" };
    return Json(errorModel, HttpStatusCode.InternalServerError);
}