线上教育系统开发中，购物车功能是如何实现的？

{
$checkToken=\App\checkToken($uid,$token);
  if($checkToken==700){
   $rs['code'] = $checkToken;
   $rs['msg'] = \PhalApi\T('您的登陆状态失效，请重新登陆！');
   return $rs;
}

        if($type<0 || $type>1 || $typeid<1){
            $rs['code'] = 1001;
            $rs['msg'] = \PhalApi\T('信息错误');
            return $rs;
        }

$where2=[
            'uid'=>$data['uid'],
            'type'=>$data['type'],
            'typeid'=>$data['typeid'],
        ];
        $nums2=$model->getNums($where2);
        if(!$nums2){
//购物车中不存在 则新加
            $res= $model->add($data);
            if(!$res){
                $rs['code'] = 1002;
                $rs['msg'] = \PhalApi\T('添加失败，请重试');
                return $rs;
            }
        }else{
//购物车中已存在 则更新状态为已选中
            $data2=[
                'isselect'=>1,
            ];
            $model->update($where2,$data2);
        }
//获取当前购物车中的商品数量 返回给APP更新
        $where=[
            'uid'=>$data['uid'],
        ];
        $nums=$model->getNums($where);
        $info['nums']=$nums;