hook_form_alter

5 core.php	`hook_form_alter($form_id, &$form)`
6 core.php	`hook_form_alter(&$form, &$form_state, $form_id)`
7 system.api.php	`hook_form_alter(&$form, &$form_state, $form_id)`
8 system.api.php	`hook_form_alter(&$form, &$form_state, $form_id)`

Perform alterations before a form is rendered.

One popular use of this hook is to add form elements to the node form. When altering a node form, the node object can be accessed at $form['#node'].

In addition to hook_form_alter(), which is called for all forms, there are two more specific form hooks available. The first, hook_form_BASE_FORM_ID_alter(), allows targeting of a form/forms via a base form (if one exists). The second, hook_form_FORM_ID_alter(), can be used to target a specific form directly.

The call order is as follows: all existing form alter functions are called for module A, then all for module B, etc., followed by all for any base theme(s), and finally for the theme itself. The module order is determined by system weight, then by module name.

Within each module, form alter hooks are called in the following order: first, hook_form_alter(); second, hook_form_BASE_FORM_ID_alter(); third, hook_form_FORM_ID_alter(). So, for each module, the more general hooks are called first followed by the more specific.

Parameters

$form: Nested array of form elements that comprise the form.

$form_state: A keyed array containing the current state of the form. The arguments that drupal_get_form() was originally called with are available in the array $form_state['build_info']['args'].

$form_id: String representing the name of the form itself. Typically this is the name of the function that generated the form.

44 functions implement hook_form_alter()

File

modules/system/system.api.php, line 1616: Hooks provided by Drupal core and the System module.

Code

<?php
function hook_form_alter(&$form, &$form_state, $form_id) {
  if (isset($form['type']) && $form['type']['#value'] . '_node_settings' == $form_id) {
    $form['workflow']['upload_' . $form['type']['#value']] = array(
      '#type' => 'radios', 
      '#title' => t('Attachments'), 
      '#default_value' => variable_get('upload_' . $form['type']['#value'], 1), 
      '#options' => array(t('Disabled'), t('Enabled')),
    );
  }
}
?>

Comments

D7 Newbie Notes

Posted by mpapet on April 28, 2011 at 9:40pm

To modify a form, check $form['#id'] for the name of the form.

It wasn't obvious to me, but you are only supposed to modify $form.

A way to discover the name of forms is to add this line to your hook_form_alter on your dev site

hook_form_alter{

watchdog('cg_volunteer', 'cg form_alter has run %formly', array('%formly' => $form['#id']), WATCHDOG_NOTICE, $link = NULL);
}

The best way to do that is

Posted by seanr on January 25, 2012 at 10:06pm

The best way to do that is with drupal_set_message, or even better with the devel module's dsm() function. Then you can do handy stuff like this:

<?php
function example_form_alter(&$form, &$form_state, $form_id) {
  dsm($form_id);  // print form ID to messages
  dsm($form);  // pretty print array using Krumo to messages
}
?>

That way you get it right there in the page you're looking at without having to go dig around in the watchdog. Here's the equivalent without devel (though why you wouldn't want to use devel I don't know...):

<?php
function example_form_alter(&$form, &$form_state, $form_id) {
  drupal_set_message($form_id);  // print form ID to messages
  drupal_set_message(print_r($form, TRUE));  // print array to messages
}
?>

One obvious advantage of using devel's dsm() function is you don't even have to know wether the variable is a string, array, or object - devel takes care of all that for you so you don't have to use print_r().

hooks can be called in template.php in D7

Posted by esod on January 29, 2012 at 6:38pm

If for some reason devel is not installed:

<?php
function mytheme_form_alter(&$form, &$form_state, $form_id) {
  $print = '<pre>' . print_r($form, TRUE) . '</pre>';
  if (module_exists('devel')) {
    dsm($form_id); // print form ID to messages
  }
  else {
    drupal_set_message($form_id); // print form ID to messages
  }
  if (module_exists('devel')) {
    dsm($form); // pretty print array using Krumo to messages
  }
  else {
    drupal_set_message($print);  // print array to messages
  }
}
?>

Wrapping print_r($form, TRUE) with <pre> tags returns the variable data in a easier to read format, although Krumo is better.

Change field name of contact form

Posted by Amy123 on February 10, 2012 at 4:53pm

Hi 'am really a newbie to drupal. I need to change name of one of my fields in contact form. Can some one please help me?

Thanks

Amy

Hi Amy, A couple of things to

Posted by soulston on February 16, 2012 at 11:31am

Hi Amy,

A couple of things to note.

This is not the best place to post questions as it should be for documentation and also these comments are not in the normal support forums so no-one will see your request unless they come to this page.

Consider using drupal stack exchange for answers http://drupal.stackexchange.com/ or the normal Drupal forums http://drupal.org/forum. Other than that there are many active IRC channels such as #drupal-uk where people might be able to help you.

I'm not entirely sure which contact form you are referring to?

hook_form_alter can be used to alter almost anything in any drupal form but it requires some custom code in either a custom module or add some code in template.php in your theme as stated above (Drupal 7).

Have a look at http://drupal.org/project/stringoverrides

or install http://drupal.org/project/webform module and create your own form.

easy hook_form_alter

Posted by subhojit777 on February 16, 2012 at 3:29pm

Suppose you have created a custom module and you want to create hook_form_alter for that module. Here are some easy steps to implement and test the working of hook_form_alter.

Suppose you want to add a new field in your in your comments form , say a checkbox. You can do this using the hook_form_alter of your custom module. Before doing this make sure that writing comment is enabled in your content type. hook_form_alter takes three parameters $form, $form_date and $form_id. If you just want to see the working of form_alter then you need to worry about only $form_id.

Just write this piece of code in your mymodule.module file:

function mymodule_form_alter(&$form, $form_state, $form_id)  {
  	switch ($form_id)  {
  	 	case 'comment_form_id':
  	 		$form['your_comment_form_name'] = array (
  	 		  '#type' => 'checkbox',
  	 		  '#title' => t ('Subscribe to replies to this comment'),
  	 		);
  	 		break;
  	 }
  }

The name of comment form is of your choice.

If you are wondering what $form_id would in your case, then add this piece of code before switch($form_id):
drupal_set_message($form_id);

You will see all the form_id's of your page after refreshing the page. Just copy the form_id of your comments form and paste it in place of comment_form_id.

Enable your module and view your comments form. You will see the checkbox in there.
Even if you dont see the checkbox in your comments form, try clearing the cache. If you have followed the above steps correctly, you will surely see the checkbox in comments form.

I hope I have made myself clear :)

Thank you Mukesh for your guidance

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