I'm looking for a good/smart/clean way to globally handle errors so that if a request is Json and an exception occurs, the result should be json and not html.
Looking for either existing solutions or some info of how to build my own.
2 Answers
One common way to do this is to write a custom exception filter:
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
};
}
}
which could be registered as a global filter in Global.asax. And then simply query some action:
$.getJSON('/someController/someAction', function (result) {
if (!result.success) {
alert(result.error);
} else {
// handle the success
}
});
5 Comments
Dashu
Wouldn't this run for every exception?
Darin Dimitrov
@Dashu, yes for every exception. You could also test whether the request was an AJAX request and whether the request content type was application/json and only in this case handle the exception.
AdrianoRR
It's interesting, but how can you get your result on a
Ajax.Error event? The idea you posted was using $.getJson, so how would you do it using the full $.ajax, including the error event?Darin Dimitrov
@AdrianoRR, the error event is trigerred only if a non-200 is sent from the server.
AdrianoRR
@Darin, i know that. That's why im asking how can i return the JsonResult data to the ajax Error event. An other thing, if it reached the OnException event, wouldn't it throw a non-200 error?
This is probably doable with a custom attribute... maybe even a subclass of HandleErrorAttribute. The trick will be how to know if a controller action was going to return JSON or not. This could be as simple as suffixing those method names such as GetCustomerDetailsJson.
