1. drupal
    1. 8
    2. 7
7 – 8 form_process_machine_name($element, &$form_state)

Processes a machine-readable name form element.


$element The form element to process. Properties used:

  • #machine_name: An associative array containing:

    • exists: A function name to invoke for checking whether a submitted machine name value already exists. The submitted value is passed as argument. In most cases, an existing API or menu argument loader function can be re-used. The callback is only invoked, if the submitted value differs from the element's #default_value.
    • source: (optional) The #array_parents of the form element containing the human-readable name (i.e., as contained in the $form structure) to use as source for the machine name. Defaults to array('name').
    • label: (optional) A text to display as label for the machine name value after the human-readable name form element. Defaults to "Machine name".
    • replace_pattern: (optional) A regular expression (without delimiters) matching disallowed characters in the machine name. Defaults to '[^a-z0-9_]+'.
    • replace: (optional) A character to replace disallowed characters in the machine name via JavaScript. Defaults to '_' (underscore). When using a different character, 'replace_pattern' needs to be set accordingly.
    • error: (optional) A custom form error message string to show, if the machine name contains disallowed characters.
  • #maxlength: (optional) Should be set to the maximum allowed length of the machine name. Defaults to 64.
  • #disabled: (optional) Should be set to TRUE in case an existing machine name must not be changed after initial creation.

Related topics


includes/, line 3332

function form_process_machine_name($element, &$form_state) {
  // Apply default form element properties.
  $element += array(
    '#title' => t('Machine-readable name'), 
    '#description' => t('A unique machine-readable name. Can only contain lowercase letters, numbers, and underscores.'), 
    '#machine_name' => array(),
  // A form element that only wants to set one #machine_name property (usually
  // 'source' only) would leave all other properties undefined, if the defaults
  // were defined in hook_element_info(). Therefore, we apply the defaults here.
  $element['#machine_name'] += array(
    'source' => array('name'), 
    'target' => '#' . $element['#id'], 
    'label' => t('Machine name'), 
    'replace_pattern' => '[^a-z0-9_]+', 
    'replace' => '_',

  // The source element defaults to array('name'), but may have been overidden.
  if (empty($element['#machine_name']['source'])) {
    return $element;

  // Retrieve the form element containing the human-readable name from the
  // complete form in $form_state. By reference, because we need to append
  // a #field_suffix that will hold the live preview.
  $key_exists = NULL;
  $source = drupal_array_get_nested_value($form_state['complete form'], $element['#machine_name']['source'], $key_exists);
  if (!$key_exists) {
    return $element;

  // Append a field suffix to the source form element, which will contain
  // the live preview of the machine name.
  $suffix_id = $source['#id'] . '-machine-name-suffix';
  $source += array('#field_suffix' => '');
  $source['#field_suffix'] .= ' <small id="' . $suffix_id . '">&nbsp;</small>';

  $parents = array_merge($element['#machine_name']['source'], array('#field_suffix'));
  drupal_array_set_nested_value($form_state['complete form'], $parents, $source['#field_suffix']);

  $element['#machine_name']['suffix'] = '#' . $suffix_id;

  $js_settings = array(
    'type' => 'setting', 
    'data' => array(
      'machineName' => array(
        '#' . $source['#id'] => $element['#machine_name'],
  $element['#attached']['js'][] = 'misc/machine-name.js';
  $element['#attached']['js'][] = $js_settings;

  return $element;