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.
 *
 * @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;
    }

}