list_predefined_options.module

<?php

/**
 * @file
 * Provides reusable, predefined options for list fields.
 */

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Entity\FieldableEntityInterface;
use Drupal\Core\Field\FieldStorageDefinitionInterface;
use Drupal\field\FieldStorageConfigInterface;

/**
 * Implements hook_form_FORM_ID_alter(): field_storage_config_edit_form.
 */
function list_predefined_options_form_field_storage_config_edit_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  /** @var \Drupal\field_ui\Form\FieldStorageConfigEditForm $form */
  $formObject = $form_state->getFormObject();
  /** @var \Drupal\field\FieldStorageConfigInterface $field */
  $field = $formObject->getEntity();

  $field_types = [
    'list_float',
    'list_integer',
    'list_string',
  ];

  if (in_array($field->getType(), $field_types)) {
    $options = \Drupal::service('plugin.manager.list_options.processor')->listOptions();
    $options = ['' => t('Custom')] + $options;

    $allowed_values = $field->getSetting('allowed_values');
    $allowed_values_function = $field->getSetting('allowed_values_function');
    $settings = $field->getThirdPartySettings('list_predefined_options');
    $plugin_id = isset($settings['plugin_id']) ? $settings['plugin_id'] : NULL;

    $form['list_predefined_options_plugin_id'] = [
      '#type' => 'select',
      '#title' => t('Allowed values'),
      '#options' => $options,
      '#default_value' => $plugin_id,
      '#ajax' => [
        'callback' => 'list_predefined_options_form_field_storage_config_form_ajax_callback',
        'wrapper' => 'edit-settings',
        'event' => 'change',
      ],
      '#weight' => -20,
    ];

    $form['settings']['#type'] = 'container';
    $form['settings']['allowed_values']['#access'] = TRUE;
    $form['settings']['allowed_values_function']['#access'] = FALSE;
    if (isset($plugin_id)) {
      /** @var \Drupal\list_predefined_options\Plugin\ListOptionsInterface $plugin */
      $plugin = \Drupal::service('plugin.manager.list_options.processor')->createInstance($plugin_id);

      $form['settings']['allowed_values'] = [
        '#type' => 'select',
        '#title' => t('Allowed values List'),
        '#description' => t('If left empty, the value of this field will be determined by the %function function.', ['%function' => $allowed_values_function]),
        '#options' => $plugin->getListOptions($field),
        '#multiple' => TRUE,
        '#default_value' => array_keys($allowed_values),
      ];
      $form['settings']['allowed_values_function']['#description'] = FALSE;
    }

    $form['#entity_builders'][] = 'list_predefined_options_form_field_storage_config_edit_form_builder';
  }
}

/**
 * AJAX callback for populating predefined option lists.
 *
 * @param array $form
 *   An associative array containing the structure of the form.
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 *   The current state of the form.
 *
 * @return array
 *   The associative array containing the new structure of the form.
 */
function list_predefined_options_form_field_storage_config_form_ajax_callback(array &$form, FormStateInterface $form_state) {
  return $form['settings'];
}

/**
 * Entity builder callback to save our settings into the field storage config.
 */
function list_predefined_options_form_field_storage_config_edit_form_builder($entity_type, $entity, &$form, FormStateInterface $form_state) {
  $plugin_id = $form_state->getValue('list_predefined_options_plugin_id');
  if (!empty($plugin_id)) {
    $entity->setThirdPartySetting('list_predefined_options', 'plugin_id', $plugin_id);

    $allowed_values = $form_state->getValue(['settings', 'allowed_values']);
    if (empty($allowed_values)) {
      $entity->setSetting('allowed_values_function', 'list_predefined_options_allowed_values');
    }
  }
  else {
    $entity->unsetThirdPartySetting('list_predefined_options', 'plugin_id');
    // If one of our plugins is being removed, remove our allowed values
    // function setting.
    if ($entity->getSetting('allowed_values_function') == 'list_predefined_options_allowed_values') {
      $entity->setSetting('allowed_values_function', '');
    }
  }
}

/**
 * Implements callback_allowed_values_function().
 */
function list_predefined_options_allowed_values(FieldStorageDefinitionInterface $definition, FieldableEntityInterface $entity = NULL, &$cacheable = TRUE) {
  $plugin_id = $definition->getThirdPartySetting('list_predefined_options', 'plugin_id');
  /** @var \Drupal\list_predefined_options\Plugin\ListOptionsInterface $plugin */
  $plugin = \Drupal::service('plugin.manager.list_options.processor')->createInstance($plugin_id);
  return $plugin->getListOptions($definition, $entity, $cacheable);
}