Rails3 ajax callback has empty xhr

Question

I'm seeing some strange behaviour with my Rails3 app. Note that I'm using the jQuery version of rails.js

From rails.js starting at line :49

 error: function (xhr, status, error) {
   el.trigger('ajax:failure', [xhr, status, error]);
   alert('error in: ' + xhr.responseText ); 
 }

From my jQuery code to execute after the form.

 .bind('ajax:failure', function(xhr, status, error) {
    alert('error in: ' + xhr.responseText );
 })

In the alert in rails.js shows the expected return text, but the alert my callback shows:

  error in: undefined

So it doesn't appear that xhr is being sent to the callback correctly. Am I doing something wrong, or is this an issue with rails.js?

Further testing shows that this applies for both the ajax:failure and ajax:success callbacks. With the ajax:success call back the server response is in status, so I didn't notice the behavior.

Answer 1

From the jQuery docs on .trigger():

"The event object is always passed as the first parameter to an event handler, but if additional parameters are specified during a .trigger() call as they are here, these parameters will be passed along to the handler as well."

The example they give is:

$('#foo').bind('custom', function(event, param1, param2) { alert(param1 + "\n" + param2); }); $('#foo').trigger('custom', ['Custom', 'Event']);

So I updated: .bind('ajax:failure', function(xhr, status, error)

to: .bind('ajax:failure', function(event, xhr, status, error)

And it's working fine now. Clearly my mistake