Question

Since ASP.NET Web API RC I was using some approach based on declaring void API controller’s operations.

I was customizing a response object DTO (instead of using HttpResponseMessage) using AOP and PostSharp, and finally this was sent to the client using HttpContext.Response.Write(...) serializing the DTO into a JSON string.

When I upgraded my solution to ASP.NET Web API RTM, this approach didn’t work anymore.

Whenever I send a response from the Web API and I receive it in the client-side, I find that the response is sent with a 204 status (NoContent) while I was setting a 200 status (OK) for the response itself.

Because this approach was working in the RC version of WebAPI I suspect that’s an unknown breaking change when WebAPI development team transitioned to RTM version.

Am I wrong?

Answer 1

As far as I know, since RTM if a POST action does not return an HttpResponseMessage the default status code is 204 (and not 200 as was back in RC). There are two things, I know, we can do to keep clients from complaining about 204.

a) Change the response message from within your action:

[HttpPost]
public HttpResponseMessage DoWork(MyModel model)
{
   // Do work
   return new HttpResponseMessage(HttpStatusCode.OK) { Content = new ObjectContent<MyModel>(model, FormatterConfig.JsonFormatter) };
}

b) Change the response in a DelegatingHandler (dirty by generic way)

public class ResponseHandler : DelegatingHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var response = base.SendAsync(request, cancellationToken);

        response.Result.StatusCode = response.Result.IsSuccessStatusCode ? System.Net.HttpStatusCode.OK : response.Result.StatusCode;
        return response;
    }
}