记一次 PHP 省市县三级联动 数据库取值

   /**
     * Notes:省市县三级联动
     * Created by depressiom
     * Date: 2022年4月14日
     */
    public function getCityData(){
        //获取一级
        $cityList = M('area')->where(['type'=>0])->select();  // 根据type 取一级
        $data = array();
        if(count($cityList)>0){
            foreach ($cityList as $v) {
                $data[$v['id']] = array(
                    "id" => $v['id'],
                    "value" => $v['area_code'],
                    "label" => $v['name'],
                    "children" => array()
                );
                //获取二级
                $cityTow = M('area')->where(['type' => 1,'parent_code'=>$v['id']])->select();  // 数据库通过关联的 一级id为 二级的父code  type为1 表示市区
                if(count($cityTow)>0) {
                    foreach ($cityTow as $l) {
                        $data[$v['id']]['children'][$l['id']] = array(
                            "id" => $l['id'],
                            "value" => $l['area_code'],  // 这里因为第一次取得是$v的值 所以出现二级与一级name一样
                            "label" => $l['name'],
                            "children" => array()
                        );
                        //获取三级
                        $cityThree = M('area')->where(['type' => 2, 'parent_code' => $l['id']])->select();  // 三级同理
                        if(count($cityTow)>0) {
                            foreach ($cityThree as $t) {
                                $data[$v['id']]['children'][$l['id']]['children'][] = array(
                                    "id" => $t['id'],
                                    "value" => $t['area_code'],
                                    "label" => $t['name'],
                                );
                            }
                        }else{
                            $msg = array(
                                "status" => -1,
                                "msg" => "获取县数据失败！",
                                "result" => null
                            );
                            $this->ajaxReturn($msg);
                            exit ();
                        }
                    }
                }else{
                    $msg = array(
                        "status" => -1,
                        "msg" => "获取市数据失败！", //.json_encode($cityTow,true) 数据不正常是前端展示查看结果
                        "result" => null
                    );
                    $this->ajaxReturn($msg);
                    exit ();
                }
            }
        }else{
            $msg = array(
                "status" => -1,
                "msg" => "获取省数据失败！",
                "result" => null
            );
            $this->ajaxReturn($msg);
            exit ();
        }
        if (count($data)<=0) {
            $msg = array(
                "status" => -1,
                "msg" => "数据出错",
                "result" => null
            );
            $this->ajaxReturn($msg);
            exit ();
        }
        //格式化数据
        $res = array();
        foreach ($data as $val) {
            $item = array();
            foreach ($val['children'] as $v) {
                $item[] = $v;
            }
            $res[] = array(
                'id' => $val['id'],
                "value" => $val['value'],  // 这里是格式化数据，因为我第一层格式已经将$data里面的字段名字改变  所以用已改变的值，就是因为这里导致找了半小时
                "label" => $val['label'],
                'children' => $item
            );
        }
        $msg = array(
            "status" => 1,
            "msg" => "数据获取成功",
            "result" => $res,
            "data"=>$data,
        );
        $this->ajaxReturn($msg);
    }

感谢大佬的分享 原作者地址