jQuery Ajax error handling, show custom exception messages

Question

Is there some way I can show custom exception messages as an alert in my jQuery AJAX error message?

For example, if I want to throw an exception on the server side v

Answer 1

This is what I did and it works so far in a MVC 5 application.

Controller's return type is ContentResult.

public ContentResult DoSomething()
{
    if(somethingIsTrue)
    {
        Response.StatusCode = 500 //Anything other than 2XX HTTP status codes should work
        Response.Write("My Message");
        return new ContentResult();
    }

    //Do something in here//
    string json = "whatever json goes here";

    return new ContentResult{Content = json, ContentType = "application/json"};
}

And on client side this is what ajax function looks like

$.ajax({
    type: "POST",
    url: URL,
    data: DATA,
    dataType: "json",
    success: function (json) {
        //Do something with the returned json object.
    },
    error: function (xhr, status, errorThrown) {
        //Here the status code can be retrieved like;
        xhr.status;

        //The message added to Response object in Controller can be retrieved as following.
        xhr.responseText;
    }
});

Answer 2

Make sure you're setting Response.StatusCode to something other than 200. Write your exception's message using Response.Write, then use...

xhr.responseText

..in your javascript.

Answer 3

You need to convert the responseText to JSON. Using JQuery:

jsonValue = jQuery.parseJSON( jqXHR.responseText );
console.log(jsonValue.Message);