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27

How do I handle exceptions thrown in a controller when jquery ajax calls an action?

For example, I would like a global javascript code that gets executed on any kind of server exception during an ajax call which displays the exception message if in debug mode or just a normal error message.

On the client side, I will call a function on the ajax error.

On the server side, Do I need to write a custom actionfilter?

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5  
See beckelmans post for a good example. Darins answer to this post is good but don't set the correct status code for an error. – Dan Oct 11 '11 at 9:50

3 Answers

up vote 53 down vote accepted

If the server sends some status code different than 200, the error callback is executed:

$.ajax({
    url: '/foo',
    success: function(result) {
        alert('yeap');
    },
    error: function(XMLHttpRequest, textStatus, errorThrown) {
        alert('oops, something bad happened');
    }
});

and to register a global error handler you could use the $.ajaxSetup() method:

$.ajaxSetup({
    error: function(XMLHttpRequest, textStatus, errorThrown) {
        alert('oops, something bad happened');
    }
});

Another way is to use JSON. So you could write a custom action filter on the server which catches exception and transforms them into JSON response:

public class MyErrorHandlerAttribute : FilterAttribute, IExceptionFilter
{
    public void OnException(ExceptionContext filterContext)
    {
        filterContext.ExceptionHandled = true;
        filterContext.Result = new JsonResult
        {
            Data = new { success = false, error = filterContext.Exception.ToString() },
            JsonRequestBehavior = JsonRequestBehavior.AllowGet
        };
    }
}

and then decorate your controller action with this attribute:

[MyErrorHandler]
public ActionResult Foo(string id)
{
    if (string.IsNullOrEmpty(id))
    {
        throw new Exception("oh no");
    }
    return Json(new { success = true });
}

and finally invoke it:

$.getJSON('/home/foo', { id: null }, function (result) {
    if (!result.success) {
        alert(result.error);
    } else {
        // handle the success
    }
});
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Thanks for this, The latter was what I was looking for. So for the asp.net mvc exception, is there a specific way I need to throw it so it can be caught by the jquery error handler? – Shawn Mclean Jan 16 '11 at 20:16
@Lol coder, no matter how you throw an exception inside the controller action the server will return 500 status code and the error callback will be executed. – Darin Dimitrov Jan 16 '11 at 20:22
Thanks, perfect, just what I was looking for. – Shawn Mclean Jan 16 '11 at 20:26
up vote 9 down vote

After googling I write a simple Exception handing based on MVC Action Filter:

public class HandleExceptionAttribute : HandleErrorAttribute
{
    public override void OnException(ExceptionContext filterContext)
    {
        if (filterContext.HttpContext.Request.IsAjaxRequest() && filterContext.Exception != null)
        {
            filterContext.HttpContext.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
            filterContext.Result = new JsonResult
            {
                JsonRequestBehavior = JsonRequestBehavior.AllowGet,
                Data = new
                {
                    filterContext.Exception.Message,
                    filterContext.Exception.StackTrace
                }
            };
            filterContext.ExceptionHandled = true;
        }
        else
        {
            base.OnException(filterContext);
        }
    }
}

and write in globol.ascx:

 public static void RegisterGlobalFilters(GlobalFilterCollection filters)
 {
      filters.Add(new HandleExceptionAttribute());
 }

and then write this script on the layout or Master page:

<script type="text/javascript">
      $(document).ajaxError(function (e, jqxhr, settings, exception) {
                       e.stopPropagation();
                       if (jqxhr != null)
                           alert(jqxhr.responseText);
                     });
</script>

Finally you should turn on custom error. and then enjoy it :)

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I can see the error in Firebug butIt is not redirecting to Error page.? – user2067567 Apr 26 at 14:20
Thanks for this! should be marked as the answer IMO as its filtering on ajax requests and inherits the correct class rather than what the HandleErrorAttribute inherits – m.t.bennett Apr 29 at 5:22
up vote 0 down vote

For handling errors from ajax calls on the client side, you assign a function to the error option of the ajax call.

To set a default globally, you can use the function described here: http://api.jquery.com/jQuery.ajaxSetup.

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