public static HttpResponseMessage CreateResponse( this HttpRequestMessage request, HttpStatusCode code, string message, IReadOnlyCollection <KeyValuePair <string, string[]> > errors) { var modelState = new { Error = new { ErrorCode = code.ErrorCode(), Message = message, ModelState = errors ?? new Dictionary <string, string[]>() } }; //var result = request.CreateResponse(code, modelState); var result = new HttpResponseMessage(code) { Content = new ObjectContent( modelState.GetType(), modelState, new JsonMediaTypeFormatter()) }; return(result); }