views_ui_add_ajax_trigger

views_ui_add_ajax_trigger(&$wrapping_element, $trigger_key, $refresh_parents)

function views_ui_add_ajax_trigger(&$wrapping_element, $trigger_key, $refresh_parents) {
  $seen_ids = &drupal_static(__FUNCTION__ . ':seen_ids', array());
  $seen_buttons = &drupal_static(__FUNCTION__ . ':seen_buttons', array());

  // Add the AJAX behavior to the triggering element.
  $triggering_element = &$wrapping_element[$trigger_key];
  $triggering_element['#ajax']['callback'] = 'views_ui_ajax_update_form';

  // We do not use \Drupal\Component\Utility\Html::getUniqueId() to get an ID
  // for the AJAX wrapper, because it remembers IDs across AJAX requests (and
  // won't reuse them), but in our case we need to use the same ID from request
  // to request so that the wrapper can be recognized by the AJAX system and
  // its content can be dynamically updated. So instead, we will keep track of
  // duplicate IDs (within a single request) on our own, later in this function.
  $triggering_element['#ajax']['wrapper'] = 'edit-view-' . implode('-', $refresh_parents) . '-wrapper';

  // Add a submit button for users who do not have JavaScript enabled. It
  // should be displayed next to the triggering element on the form.
  $button_key = $trigger_key . '_trigger_update';
  $element_info = \Drupal::service('element_info');
  $wrapping_element[$button_key] = array(
    '#type' => 'submit',
    // Hide this button when JavaScript is enabled.
    '#attributes' => array('class' => array('js-hide')),
    '#submit' => array('views_ui_nojs_submit'),
    // Add a process function to limit this button's validation errors to the
    // triggering element only. We have to do this in #process since until the
    // form API has added the #parents property to the triggering element for
    // us, we don't have any (easy) way to find out where its submitted values
    // will eventually appear in $form_state->getValues().
    '#process' => array_merge(array('views_ui_add_limited_validation'), $element_info->getInfoProperty('submit', '#process', array())),
    // Add an after-build function that inserts a wrapper around the region of
    // the form that needs to be refreshed by AJAX (so that the AJAX system can
    // detect and dynamically update it). This is done in #after_build because
    // it's a convenient place where we have automatic access to the complete
    // form array, but also to minimize the chance that the HTML we add will
    // get clobbered by code that runs after we have added it.
    '#after_build' => array_merge($element_info->getInfoProperty('submit', '#after_build', array()), array('views_ui_add_ajax_wrapper')),
  );
  // Copy #weight and #access from the triggering element to the button, so
  // that the two elements will be displayed together.
  foreach (array('#weight', '#access') as $property) {
    if (isset($triggering_element[$property])) {
      $wrapping_element[$button_key][$property] = $triggering_element[$property];
    }
  }
  // For easiest integration with the form API and the testing framework, we
  // always give the button a unique #value, rather than playing around with
  // #name. We also cast the #title to string as we will use it as an array
  // key and it may be a TranslatableMarkup.
  $button_title = !empty($triggering_element['#title']) ? (string) $triggering_element['#title'] : $trigger_key;
  if (empty($seen_buttons[$button_title])) {
    $wrapping_element[$button_key]['#value'] = t('Update "@title" choice', array(
      '@title' => $button_title,
    ));
    $seen_buttons[$button_title] = 1;
  }
  else {
    $wrapping_element[$button_key]['#value'] = t('Update "@title" choice (@number)', array(
      '@title' => $button_title,
      '@number' => ++$seen_buttons[$button_title],
    ));
  }

  // Attach custom data to the triggering element and submit button, so we can
  // use it in both the process function and AJAX callback.
  $ajax_data = array(
    'wrapper' => $triggering_element['#ajax']['wrapper'],
    'trigger_key' => $trigger_key,
    'refresh_parents' => $refresh_parents,
  );
  $seen_ids[$triggering_element['#ajax']['wrapper']] = TRUE;
  $triggering_element['#views_ui_ajax_data'] = $ajax_data;
  $wrapping_element[$button_key]['#views_ui_ajax_data'] = $ajax_data;
}