遞歸-實現省市區三級聯動

public static function linkage()
{
    //由於數據量太大，只循環了pid=1的數據 (查詢省市區的id，區域名稱,父級id)
    $data = Address::whereIn('type',[2,3,4])->get(['id','name','pid'])->toArray();
    return self::getTree($data);
}
//遞歸
public static function getTree($data,$pid =1)
{
    $list = [];
    foreach ($data as $value)
    {
        //第一次遍歷，找到父節點為1的
        if ($value['pid'] == $pid){
            //開始遞歸，查找父id為該節點id的節點
            if (!empty(self::getTree($data, $value['id']))){
                $value['childList'] = self::getTree($data, $value['id']);
            }
            $list[] = $value;
        }
    }
    return $list;