drupal_alter() form instead of form_element in AHAH callback

Not a correct approach, I think. Note that only the affected elements are going to be sent to the AHAH request, so you should NOT alter any other part of the form here.

On the other hand, you can hook_form_alter() against $form_id == 'content_add_more_js', and here inspect the form elements to see if you need to alter anything. Is there any information missing that you need to pass on to hook_form_alter()? If so, I would rather fix that.

subscribing

subscribing

The "correct" approach in Drupal6 is to rebuild the complete form even for AHAH submits, thus invoking drupal_rebuild_form -> drupal_prepare_form -> hook_form_alter as described here:

http://drupal.org/node/331941

I am writing a CCK userreference widget for inline user registration and came across the non-standard invocation of hook_form_alter issue as I need a group of radios across all widgets.

As a quick hack, one can replace $form[$field['field_name']][$field['field_name'].'_add_more']['#ahah']['path'] of the 'Add another item' submit button in hook_form_alter with the path of a custom #ahah callback. I did this, using the "correct" approach in the #ahah callback and fiddled with $form_state['item_count'][$field_name]. It works for me.

There remains the problem with #required, not yet provided, input elements further down the rendered form as they will get validated for every AHAH submit. I solved the problem by recursively un- and rerequiring the form_elements but it is not pretty and seems like an oversight of the whole AHAH approach in Drupal.

@sirkitree: Needs review status means there's a patch for review. I think we cannot change the form_id there because we will be breaking 3rd party code that relies on that.

@sradomski: I see what you mean, but I'm afraid it is now too late in the life cycle of CCK for D6 to change these things. We cannot break existing code. Also please note the AHAH callback attached to "Add more values" button does not validate for form. It's only meant to add a new value to that multiple values field.

I would say here this is "by design", but I leave it as "needs work" in case there's anything that can be added to the hook_form_alter() against 'content_add_more_js' that helps implement this hook. Please, note you can still use FAPI callback for after_built, also pre_render, post_render callbacks. Just think this AHAH process is just meant to change the part of the form related to the "Add more items" button just pressed by the user. The rest of the form should not be altered here because it is not sent back with the AHAH response.

I would even say if you need advanced processing that the AHAH callback provided by CCK does not allow you, then you're free to replace this callback by your own. This approach will not affect the rest of the CCK users, and this is pretty important at this moment in time.

Well, I just added a page to the CCK handbook that describes a method to alter the "Add more items" button text that even works for multigroups.

- Code snippet: How to change the label of the "Add more items" button.

The after_build callback is executed when all elements are already expanded, so the same method could be used to alter almost anything else related to the form elements that exist in the form. Note that this method also works when the AHAH request is processed.

It seems to me there's no need to change the hooks invoked from the AHAH callback attached to the "Add more items" buttons.

Please, feel free to re-open with an example of something that cannot be done using hook_form_alter() + after_build callback.

Subscribing. Markus, I'm trying to use the approach that you describe in your write-up to edit the "title" label on the AHAH callback but am having a bit of a time finding the name of the form to pass to the _node_form_element_alter_register function. I'll post my solution as soon as I figure it out. Or, if anyone else knows this off the top of their heads, please let me know.

-sean

Aha, I figured it out. I just needed to dive deeper into the form's array. Picking up on Markus's post:

/**
* Implementation of hook_node_form_element_alter().
*/
function common_node_form_element_alter($name, &$element) {
  $element['data']['title']['#title'] = 'Custom title';
}