public void OnException(ExceptionContext filterContext)
        {
            OnFilterExecution(filterContext);

            filterContext.ExceptionHandled = true;
            string message = OnException(filterContext.Exception);

            if (Request.IsAjaxRequest() && !filterContext.IsPartialViewRequest())
            {
                filterContext.Result = new HttpStatusCodeResult(HttpStatusCode.InternalServerError, message);
            }
            else
            {
                OnRedirect(filterContext.Exception, message);
            }
        }