/**
 * Adds a JOIN clause to the query using the i18n relation
 *
 * @param     string $locale Locale to use for the join condition, e.g. 'fr_FR'
 * @param     string $relationAlias optional alias for the relation
 * @param     string $joinType Accepted values are null, 'left join', 'right join', 'inner join'. Defaults to left join.
 *
 * @return     The current query, for fluid interface
 */
public function joinI18n($locale = '', $relationAlias = null, $joinType = Criteria::LEFT_JOIN)
{
    $relationName = $relationAlias ? $relationAlias : '';

    return $this
        ->join($relationAlias, $joinType)
        ->addJoinCondition($relationName, $relationName . '. = ?', $locale);
}