递归删除（自上而下删）---laravel 静态方法

//定义一个静态方法

public static function del($id){    $document = Document::find($id);    if (!$document) {        return false;    }    $documentOne = Document::where('parent_id', $id)->get();    if (count($documentOne) != 0) {        $document->delete();        foreach ($documentOne as $item){            self::del($item->id);        }        return true;    } else {        $document->delete();        return true;    }

//调用静态方法
public function deleteDocument(Request $request, $id){    self::del($id);    return response()->json(['code' => 200, 'msg' => '删除成功']);}