Role.php

<?php

namespace Drupal\user\Plugin\migrate\source\d7;

use Drupal\migrate\Row;
use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;

/**
 * Drupal 7 role source from database.
 *
 * For available configuration keys, refer to the parent classes.
 *
 * @see \Drupal\migrate\Plugin\migrate\source\SqlBase
 * @see \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
 *
 * @MigrateSource(
 *   id = "d7_user_role",
 *   source_module = "user"
 * )
 */
class Role extends DrupalSqlBase {
  
  /**
   * {@inheritdoc}
   */
  public function query() {
    return $this->select('role', 'r')
      ->fields('r');
  }
  
  /**
   * {@inheritdoc}
   */
  public function fields() {
    return [
      'rid' => $this->t('Role ID.'),
      'name' => $this->t('The name of the user role.'),
      'weight' => $this->t('The weight of the role.'),
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function prepareRow(Row $row) {
    $permissions = $this->select('role_permission', 'rp')
      ->fields('rp', [
      'permission',
    ])
      ->condition('rid', $row->getSourceProperty('rid'))
      ->execute()
      ->fetchCol();
    $row->setSourceProperty('permissions', $permissions);
    return parent::prepareRow($row);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getIds() {
    $ids['rid']['type'] = 'integer';
    return $ids;
  }

}