abstract class AutocompleteWidgetBase

AutocompleteTagsWidget.php in drupal/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/field/widget/AutocompleteTagsWidget.php

Contains \Drupal\entity_reference\Plugin\field\widget\AutocompleteTagsWidget.

AutocompleteWidget.php in drupal/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/field/widget/AutocompleteWidget.php

Contains \Drupal\entity_reference\Plugin\field\widget\AutocompleteWidget.

abstract class AutocompleteWidgetBase extends WidgetBase {

  /**
   * Overrides \Drupal\field\Plugin\Type\Widget\WidgetBase::settingsForm().
   */
  public function settingsForm(array $form, array &$form_state) {
    $element['match_operator'] = array(
      '#type' => 'radios',
      '#title' => t('Autocomplete matching'),
      '#default_value' => $this
        ->getSetting('match_operator'),
      '#options' => array(
        'STARTS_WITH' => t('Starts with'),
        'CONTAINS' => t('Contains'),
      ),
      '#description' => t('Select the method used to collect autocomplete suggestions. Note that <em>Contains</em> can cause performance issues on sites with thousands of entities.'),
    );
    $element['size'] = array(
      '#type' => 'number',
      '#title' => t('Size of textfield'),
      '#default_value' => $this
        ->getSetting('size'),
      '#min' => 1,
      '#required' => TRUE,
    );
    $element['placeholder'] = array(
      '#type' => 'textfield',
      '#title' => t('Placeholder'),
      '#default_value' => $this
        ->getSetting('placeholder'),
      '#description' => t('Text that will be shown inside the field until a value is entered. This hint is usually a sample value or a brief description of the expected format.'),
    );
    return $element;
  }

  /**
   * Implements \Drupal\field\Plugin\Type\Widget\WidgetInterface::formElement().
   */
  public function formElement(array $items, $delta, array $element, $langcode, array &$form, array &$form_state) {
    global $user;
    $instance = $this->instance;
    $field = $this->field;
    $entity = isset($element['#entity']) ? $element['#entity'] : NULL;

    // Prepare the autocomplete path.
    $autocomplete_path = $this
      ->getSetting('autocomplete_path');
    $autocomplete_path .= '/' . $field['field_name'] . '/' . $instance['entity_type'] . '/' . $instance['bundle'] . '/';

    // Use <NULL> as a placeholder in the URL when we don't have an entity.
    // Most web servers collapse two consecutive slashes.
    $id = 'NULL';
    if ($entity && ($entity_id = $entity
      ->id())) {
      $id = $entity_id;
    }
    $autocomplete_path .= $id;
    $element += array(
      '#type' => 'textfield',
      '#maxlength' => 1024,
      '#default_value' => implode(', ', $this
        ->getLabels($items)),
      '#autocomplete_path' => $autocomplete_path,
      '#size' => $this
        ->getSetting('size'),
      '#placeholder' => $this
        ->getSetting('placeholder'),
      '#element_validate' => array(
        array(
          $this,
          'elementValidate',
        ),
      ),
      // @todo: Use wrapper to get the user if exists or needed.
      '#autocreate_uid' => isset($entity->uid) ? $entity->uid : $user->uid,
    );
    return array(
      'target_id' => $element,
    );
  }

  /**
   * Overrides \Drupal\field\Plugin\Type\Widget\WidgetBase::errorElement().
   */
  public function errorElement(array $element, array $error, array $form, array &$form_state) {
    return $element['target_id'];
  }

  /**
   * Validates an element.
   */
  public function elementValidate($element, &$form_state, $form) {
  }

  /**
   * Gets the entity labels.
   */
  protected function getLabels(array $items) {
    $entity_ids = array();
    $entity_labels = array();

    // Build an array of entity IDs.
    foreach ($items as $item) {
      $entity_ids[] = $item['target_id'];
    }

    // Load those entities and loop through them to extract their labels.
    $entities = entity_load_multiple($this->field['settings']['target_type'], $entity_ids);
    foreach ($entities as $entity_id => $entity_item) {
      $label = $entity_item
        ->label();
      $key = "{$label} ({$entity_id})";

      // Labels containing commas or quotes must be wrapped in quotes.
      if (strpos($key, ',') !== FALSE || strpos($key, '"') !== FALSE) {
        $key = '"' . str_replace('"', '""', $key) . '"';
      }
      $entity_labels[] = $key;
    }
    return $entity_labels;
  }

  /**
   * Creates a new entity from a label entered in the autocomplete input.
   *
   * @param string $label
   *   The entity label.
   * @param int $uid
   *   The entity uid.
   *
   * @return \Drupal\Core\Entity\EntityInterface
   */
  protected function createNewEntity($label, $uid) {
    $entity_manager = \Drupal::entityManager();
    $target_type = $this->field['settings']['target_type'];

    // Get the bundle.
    if (!empty($this->instance['settings']['handler_settings']['target_bundles']) && count($this->instance['settings']['handler_settings']['target_bundles']) == 1) {
      $bundle = reset($this->instance['settings']['handler_settings']['target_bundles']);
    }
    else {
      $bundles = entity_get_bundles($target_type);
      $bundle = reset($bundles);
    }
    $entity_info = $entity_manager
      ->getDefinition($target_type);
    $bundle_key = $entity_info['entity_keys']['bundle'];
    $label_key = $entity_info['entity_keys']['label'];
    return $entity_manager
      ->getStorageController($target_type)
      ->create(array(
      $label_key => $label,
      $bundle_key => $bundle,
      'uid' => $uid,
    ));
  }

}