protected function filterTimestamp(&$query, $attr = 'updated_at')
    {
        if (!is_null($this->{$attr}) && strpos($this->{$attr}, ' - ') !== false ) {
            list($start_date, $end_date) = explode(' - ', $this->{$attr});
            $query->andFilterWhere(['>=', $attr, (int)strtotime($start_date)]);
            $query->andFilterWhere(['<=', $attr, (int)strtotime($end_date) + 24 * 3600]);
        }
    }