public function callbackChangeSortIndex($new, $old)
    {
        // get old position
        $newPos = (new Query)->select([$this->sortIndexFieldName])->from($this->refTableName)->where([$this->imageIdFieldName => $new['originalImageId']])->scalar();
        $oldPos = (new Query)->select([$this->sortIndexFieldName])->from($this->refTableName)->where([$this->imageIdFieldName => $old['originalImageId']])->scalar();
        
        // switch positions
        $changeNewPos = Yii::$app->db->createCommand()->update($this->refTableName, [$this->sortIndexFieldName => $oldPos], [
            $this->imageIdFieldName => $new['originalImageId'],
            $this->refFieldName => $this->itemId,
        ])->execute();
        
        $changeOldPos = Yii::$app->db->createCommand()->update($this->refTableName, [$this->sortIndexFieldName => $newPos], [
            $this->imageIdFieldName => $old['originalImageId'],
            $this->refFieldName => $this->itemId,
        ])->execute();
        
        return true;
    }