multiselect.module

<?php

/**
 * @file
 * Allows users to select multiple items in an easier way than the normal node-reference widget.
 */

use Drupal\Core\Render\Element;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Template\Attribute;
use Drupal\multiselect\Element\Multiselect;

/**
 * Implements hook_help().
 */
function multiselect_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.multiselect':
      $output = '';
      $output .= '<p>' . t('Provides a CCK and Form API widget for editing fields that allows users to select from a list of options in a left box and have them visually moved into the right box when options are chosen.') . '</p>';
      $output .= '<h3>' . t('Methods of Implementing a Multiselect Widget') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt><h5>' . t('Method 1: Using CCK') . '</h5></dt>';
      $output .= '<dd>' . t('When creating a new content field, select "Multiselect" as your widget type. You can use Multiselect on fields of type "list", "list_text", "list_number", "node_reference", "taxonomy_term_reference", and "user_reference".') . '</dd>';
      $output .= '<dt><h5>' . t('Method 2: Coding Your Own Module') . '</h5></dt>';
      $output .= '<dd>' . t('If you\'re developing a custom module and wish to use the Multiselect widget in place of a traditional "select" widget, you may use the Drupal 8 Form API.') . '</dd>';
      $output .= '</dl>';
      return $output;
  }
}

/**
 * Implements hook_page_build().
 */
function multiselect_page_build(&$page) {
  $config = \Drupal::config('multiselect.settings');
  $page['#attached']['js'][] = array(
    'data' => array(
      'multiselect' => array('widths' => $config->get('multiselect.widths')),
    ),
    'type' => 'setting',
  );
}

/**
 * Implements hook_theme().
 */
function multiselect_theme() {
  return array(
    'multiselect' => array(
      'arguments' => array('element' => NULL),
      'render element' => 'element',
      'template' => 'multiselect',
    ),
  );
}

/**
 * Prepares variables for multiselect element templates.
 *
 * Default template: multiselect.html.twig.
 *
 * @param $variables
 *   An associative array containing:
 *   - element: An associative array containing the properties of the element.
 *     Properties used: #title, #value, #options, #description, #extra,
 *     #multiple, #required, #name, #attributes, #size.
 */
function template_preprocess_multiselect(&$variables) {
  $element = $variables['element'];
  Element::setAttributes($element, array('id', 'name', 'size', 'required'));

  $available_options = Multiselect::getOptions('available', $element);
  $available_size = min(count($available_options), 10);

  $selected_options = Multiselect::getOptions('selected', $element);
  $selected_size = min(count($selected_options), 10);
  $total_size = $available_size + $selected_size;

  $variables['multiselect'] = array(
    'available' => array(
      'id' => $element['#attributes']['id'] . '-available',
      'label' => t('Available Options'),
      'attributes' => array(
        'id' => $element['#attributes']['id'] . '-available',
        'size' => $total_size,
      ),
      'options' => $available_options,
    ),
    'selected' => array(
      'id' => $element['#attributes']['id'],
      'label' => t('Selected Options'),
      'attributes' => $element['#attributes'],
      'options' => $selected_options,
    ),
    'labels' => array(
      'add' => t('Add'),
      'remove' => t('Remove'),
    ),
  );

  // Prepare selected attributes.
  $variables['multiselect']['selected']['attributes']['size'] = $total_size;

  // Prepare attributes for available select.
  foreach (array('multiple', 'required', 'class') as $key) {
    $element_key = "#{$key}";
    if (isset($element[$element_key])) {
      $variables['multiselect']['available']['attributes'][$key] = $element[$element_key];
    }
  }
  // Prepare attributes.
  $multiselect = &$variables['multiselect'];
  foreach (array('available', 'selected') as $key) {
    $multiselect[$key]['attributes']['class'][] = 'multiselect-' . $key;
    $multiselect[$key]['attributes']['class'][] = 'form-multiselect';
    if (isset($multiselect[$key]['attributes']) && !($multiselect[$key]['attributes'] instanceof Attribute)) {
      if ($multiselect[$key]['attributes']) {
        $multiselect[$key]['attributes'] = new Attribute($multiselect[$key]['attributes']);
      }
    }
  }
}