multiselect.module

<?php

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

use Drupal\Component\Utility\String;
use Drupal\Core\Render\Element;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Template\Attribute;
use Drupal\Component\Utility\SafeMarkup;

/**
 * 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'));
  //_form_set_attributes($element, array('form-multiselect'));

  $variables['multiselect'] = array(
    'available' => array(
      'id' => $element['#attributes']['id'] . '-available',
      'label' => t('Available Options'),
      'attributes' => array(
        'id' => $element['#attributes']['id'] . '-available',
      ),
      'options' => multiselect_get_options('available', $element),
    ),
    'selected' => array(
      'id' => $element['#attributes']['id'],
      'label' => t('Selected Options'),
      'attributes' => $element['#attributes'],
      'options' => multiselect_get_options('selected', $element),
    ),
    'labels' => array(
      'add' => t('Add'),
      'remove' => t('Remove'),
    ),
  );
  // Prepare attributes for available select.
  foreach (array('multiple', 'required', 'class') as $key) {
    if (isset($element['#attributes'][$key])) {
      $variables['multiselect']['available']['attributes'][$key] = $element['#attributes'][$key];
    }
  }
  // Prepare attributes.
  $multiselect = &$variables['multiselect'];
  foreach (array('available', 'selected') as $key) {
    $multiselect[$key]['attributes']['class'][] = 'multiselect-' . $key;
    $multiselect[$key]['attributes']['class'][] = 'form-select';
    if (isset($multiselect[$key]['attributes']) && !($multiselect[$key]['attributes'] instanceof Attribute)) {
      if ($multiselect[$key]['attributes']) {
        $multiselect[$key]['attributes'] = new Attribute($multiselect[$key]['attributes']);
      }
    }
  }
}

/**
 * Helper function for get multiselect options.
 *
 * @param string $type
 *   The type of options.
 * @param $element
 *   An associative array containing the properties of the element.
 * @param $choices
 *   Mixed: Either an associative array of items to list as choices, or an
 *   object with an 'option' member that is an associative array. This
 *   parameter is only used internally and should not be passed.
 *
 * @return
 *   An HTML string of options for the multiselect form element.
 */
function multiselect_get_options($type, $element, $choices = NULL) {
  if (!isset($choices)) {
    if (empty($element['#options'])) {
      return '';
    }
    $choices = $element['#options'];
  }
  // array_key_exists() accommodates the rare event where $element['#value'] is NULL.
  // isset() fails in this situation.
  $value_valid = isset($element['#value']) || array_key_exists('#value', $element);
  $value_is_array = $value_valid && is_array($element['#value']);
  // Check if the element is multiple select and no value has been selected.
  $empty_value = (empty($element['#value']) && !empty($element['#multiple']));
  $options = '';
  foreach ($choices as $key => $choice) {
    if (is_array($choice)) {
      $options .= '<optgroup label="' . String::checkPlain($key) . '">';
      $options .= multiselect_get_options($type, $element, $choice);
      $options .= '</optgroup>';
    }
    elseif (is_object($choice) && isset($choice->option)) {
      $options .= multiselect_get_options($type, $element, $choice->option);
    }
    else {
      $key = (string) $key;
      $empty_choice = $empty_value && $key == '_none';
      switch ($type) {
        case 'available':
          if (!($value_valid && ((!$value_is_array && (string) $element['#value'] === $key || ($value_is_array && in_array($key, $element['#value']))) || $empty_choice))) {
            $options .= '<option value="' . String::checkPlain($key) . '">' . String::checkPlain($choice) . '</option>';
          }
          break;

        case 'selected':
          if ($value_valid && ((!$value_is_array && (string) $element['#value'] === $key || ($value_is_array && in_array($key, $element['#value']))) || $empty_choice)) {
            $options .= '<option value="' . String::checkPlain($key) . '" selected="selected">' . String::checkPlain($choice) . '</option>';
          }
          break;
      }
    }
  }
  return SafeMarkup::set($options);
}