EloquentFilter\ModelFilter::relationIsJoined PHP Метод

    public function relationIsJoined($relation)
    {
        if ($this->_joinedTables === null) {
            $this->_joinedTables = $this->getJoinedTables();
        }
        return in_array($this->getRelatedTable($relation), $this->_joinedTables);
    }