hook_element_info

7 system.api.php hook_element_info()
8 system.api.php hook_element_info()

Allows modules to declare their own Forms API element types and specify their default values.

This hook allows modules to declare their own form element types and to specify their default values. The values returned by this hook will be merged with the elements returned by hook_form() implementations and so can return defaults for any Form APIs keys in addition to those explicitly mentioned below.

Each of the form element types defined by this hook is assumed to have a matching theme function, e.g. theme_elementtype(), which should be registered with hook_theme() as normal.

For more information about custom element types see the explanation at http://drupal.org/node/169815.

Return value

An associative array describing the element types being defined. The array contains a sub-array for each element type, with the machine-readable type name as the key. Each sub-array has a number of possible attributes:

  • "#input": boolean indicating whether or not this element carries a value (even if it's hidden).
  • "#process": array of callback functions taking $element, $form_state, and $complete_form.
  • "#after_build": array of callback functions taking $element and $form_state.
  • "#validate": array of callback functions taking $form and $form_state.
  • "#element_validate": array of callback functions taking $element and $form_state.
  • "#pre_render": array of callback functions taking $element and $form_state.
  • "#post_render": array of callback functions taking $element and $form_state.
  • "#submit": array of callback functions taking $form and $form_state.
  • "#title_display": optional string indicating if and how #title should be displayed, see theme_form_element() and theme_form_element_label().

See also

hook_element_info_alter()

system_element_info()

Related topics

6 functions implement hook_element_info()

1 invocation of hook_element_info()

File

modules/system/system.api.php, line 643
Hooks provided by Drupal core and the System module.

Code

function hook_element_info() {
  $types['filter_format'] = array(
    '#input' => TRUE,
  );
  return $types;
}

Comments

Drupal 6

In Drupal 6 and before, this was http://api.drupal.org/api/function/hook_elements/6

Missing some attributes...

'#theme' specifies an array of theme functions that are called to theme the element.

'#theme_wrappers' specifics an array of theme functions that are called to wrap around the element -- often this is array('form_element')

Custom Attributes

It looks like you can define your own attributes here.

Be careful naming '#process' callback

I'm in the process of porting my own modules to D7 and had some major frustration with my "#process" callbacks from the D6 version not working properly.

I just realized that Drupal 7 contains a new hook called "hook_process()." That means you need to avoid naming your "#process" callback something like MODULENAME_process() -- Drupal will think that's a different hook (it has something to do with theming).

#value_callback attribute missing

<?php
function your_module_element_info() { 
  return array(
   
'new_form_type' => array(
     
'#input' => TRUE,
     
'#tree' => TRUE,
     
'#process' => array('_new_form_type_process'),
     
'#value_callback' => '_new_form_type_value_callback',
  ));
}

function
_new_form_type_value_callback($element, $input = FALSE, &$form_state) {
  if (
$input !== FALSE) {
   
// Process $input
 
} elseif (!empty($element['#default_value'])) {
    return
$element['#default_value'];
  }
 
  return;
}
?>

Callback

It seems '#pre_render' callbacks accept only one argument, $element.

#base_type

Had me puzzled since it could be found on http://api.drupal.org/api/drupal/developer!topics!forms_api_reference.html/7 but appears to be non-standard

See:

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