CODEWITHSUNDEEP
ajaxasp.net-mvcjqueryerror-handling
Adam Levitt
Adam Levitt

Reputation: 10476

ASP.NET MVC Ajax Error returning view instead of ajax

I'm making an ASP.NET MVC call to a method via AJAX and the error throws an exception. I'd like the message of the exception to be passed back to the client, and I'd prefer not to have to catch the exception. Something like this:

[HttpPost]
public ActionResult AddUser(User user) {
  if (UserIsValid(user)) {
    return Json(new { resultText = "Success!" });
  } 
  throw new Exception("The user was invalid.  Please fill out the entire form.");
}

I'm seeing in my firebug response an HTML page 

<!DOCTYPE html>
<html>
    <head>
        <title>"The user was invalid.  Please fill out the entire form."</title>
        .....

I'd like to not be forced to use a try catch block to do this. Is there a way to automatically get the jQuery $(document).ajaxError(function () {} to read in this exception message? Is this bad practice? Can I override the controller OnException? Or do I have to try/catch and return JSON?

Something like this would be nice:

$(document).ajaxError(function (data) {
    alert(data.title);        
});

Upvotes: 4

Views: 7266

Answers (2)

Francis
Francis

Reputation: 1244

You can do this with a custom filter:

$(document).ajaxError(function(event, jqxhr) {
    console.log(jqxhr.responseText);
});

-

[HttpPost]
[CustomHandleErrorAttribute]
public JsonResult Foo(bool isTrue)
{
    if (isTrue)
    {
        return Json(new { Foo = "Bar" });
    }
    throw new HttpException(404, "Oh noes...");
}

public class CustomHandleErrorAttribute : HandleErrorAttribute
{
    public override void OnException(ExceptionContext filterContext)
    {
        var exception = filterContext.Exception;
        var statusCode = new HttpException(null, exception).GetHttpCode();

        filterContext.Result = new JsonResult
        {
            JsonRequestBehavior = JsonRequestBehavior.AllowGet, //Not necessary for this example
            Data = new
            {
                error = true,
                message = filterContext.Exception.Message
            }
        };

        filterContext.ExceptionHandled = true;
        filterContext.HttpContext.Response.Clear();
        filterContext.HttpContext.Response.StatusCode = statusCode;  
        filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
    }
}

Somewhat inspired by this blogpost: http://www.prideparrot.com/blog/archive/2012/5/exception_handling_in_asp_net_mvc

Upvotes: 8

Andy T
Andy T

Reputation: 9881

Rather than handle an exception that was raised by the server, why not have a flag in the JSON response?

[HttpPost]
public ActionResult AddUser(User user) {
  if (UserIsValid(user)) {
    return Json(new { success = true, resultText = "Success!" });
  } 

  return Json(new { success = false, resultText = "The user was invalid.  Please fill out the entire form." });
}

Upvotes: 0

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