public function eventBeforeInsert()
    {
        $item = self::find()->where([
            'nav_container_id' => $this->nav_container_id,
            'parent_nav_id' => $this->parent_nav_id
        ])->orderBy('sort_index DESC')->limit(1)->asArray()->one();
        if (!$item) {
            $this->sort_index = 1;
        } else {
            $this->sort_index = $item['sort_index'] + 1;
        }
    }