protected function reorder($parentId = 0)
    {
        $query = call_user_func("$this->ownerClassName::find")
            ->select("$this->primaryKey")
            ->orderBy("$this->sortField, $this->primaryKey");
        if ( $this->parentIdField ) {
            $query->where([ $this->parentIdField => $parentId ]);
        }
        $data = array_map('intval', $query->column());
        foreach ( $data as $i => $itemPK ) {
            call_user_func("$this->ownerClassName::updateAll",
                [ $this->sortField => ($i + 1) * 100 ],
                [ $this->primaryKey => $itemPK ]);
        }
    }