ASP.NET MVC Ajax Actions results enveloping

Question

Hello, I would like to have every result of any AJAX call on ASP.NET MVC to be enveloped to a JSON object which should be like: AjaxResult { status, data }

where status will contain a enumeration value describing if the call was successful, erroneous, authentication expired etc. This will enable client side code to be able to redirect to the login page etc.

I tried catching Ajax Requests by overriding OnActionExecuted, and trying to render the returned by the corresponding action result using the following code, but this solution seems operating slow. Do you have some better idea?

protected override void OnActionExecuted(ActionExecutedContext filterContext)
{
    if (filterContext.HttpContext.Request.IsAjaxRequest() && filterContext.Exception == null)
    {
        if (filterContext.Result.GetType() == typeof(ViewResult))
            {
                ViewResult viewResultTemp = (ViewResult)filterContext.Result;
    using (StringWriter sw = new StringWriter())
    {
     ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, viewResultTemp.ViewName);
     ViewContext viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
     viewResult.View.Render(viewContext, sw);
     var ajaxReply = new AjaxReply(AjaxReplyStatus.Success, string.Empty, sw.ToString());
     filterContext.Result = new JsonResult {Data = ajaxReply};
    }
   }
   else if (filterContext.Result.GetType() == typeof(PartialViewResult))
   {
    PartialViewResult partialViewResultTemp = (PartialViewResult)filterContext.Result;
    using (StringWriter sw = new StringWriter())
    {
     ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, partialViewResultTemp.ViewName);
     ViewContext viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
     viewResult.View.Render(viewContext, sw);
     var ajaxReply = new AjaxReply(AjaxReplyStatus.Success, string.Empty, sw.ToString());
     filterContext.Result = new JsonResult { Data = ajaxReply };
    }
   }
   else if (filterContext.Result.GetType() == typeof(JsonResult))
   {
    JsonResult jsonResult = (JsonResult)filterContext.Result;
    JavaScriptSerializer javaScriptSerializer = new JavaScriptSerializer();
    string jsonData = javaScriptSerializer.Serialize(jsonResult.Data);
    var ajaxReply = new AjaxReply(AjaxReplyStatus.Success, string.Empty, jsonData);
    filterContext.Result = new JsonResult { Data = ajaxReply };
   }
  }
 }
}