Adding #ajax to checkboxes and getting selected values in callback

Question

I've been trying to use #ajax callbacks on a form. I've got this working with radio buttons, so when I've debugged the form I get the value associated with the radio button as '#value' under 'triggering_element' in $form_state; what I'm struggling with is doing the same thing with a group of checkboxes. The first checkbox checked seems to work correctly, and I can see the correct value, but if I click a second checkbox, the value doesn't come through correctly (triggering element is the field that was returned in the previous #ajax callback for some reason??) and '#value' is a string and not an array as I would have expected. Also $form_state['#values'] doesn't contain the previously selected checkbox or the current checkbox.

How do you correctly add #ajax to an element of type 'checkboxes' and how is it possible to get the value of all checked checkboxes when the ajax callback is fired?

Answer 1

There is a module that can trigger an ajax callback on a form (content type) maybe that modules solves your issue http://drupal.org/project/conditional_fields.

Answer 2

I hope this may help you. This example is from Drupal Example module which is creating checkboxes through ajax. Compare your code with it and hopefully will find the culprit.

Drupal Ajaxified Checkboxes example