rng-3.x-dev/src/Plugin/views/field/RegistrationDateStringField.php

<?php

namespace Drupal\rng\Plugin\views\field;

use Drupal\views\Plugin\views\field\FieldPluginBase;
use Drupal\views\ResultRow;

/**
 * A handler to provide a field that is completely custom by the administrator.
 *
 * @ingroup views_field_handlers
 *
 * @ViewsField("registration_date_string_field")
 */
class RegistrationDateStringField extends FieldPluginBase {

  /**
   * {@inheritdoc}
   */
  public function usesGroupBy() {
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function query() {
    // Do nothing -- to override the parent query.
  }

  /**
   * {@inheritdoc}
   */
  protected function defineOptions() {
    $options = parent::defineOptions();

    $options['hide_alter_empty'] = ['default' => FALSE];
    return $options;
  }

  /**
   * {@inheritdoc}
   */
  public function render(ResultRow $values) {
    $object = $values->_entity;
    if ($object && method_exists($object, 'getDateString')) {
      return $object->getDateString();
    }

  }

}