在线教育平台开发过程中，购物功能是如何实现的？

if($uid<1 || $payid<1 || $payid>2 || $goods==''){
   $rs['code']=1001;
   $rs['msg']=\PhalApi\T('信息错误');
   return $rs;
  }

   $checkToken=\App\checkToken($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;
  }

$goods_a=json_decode($goods,true);
        if(!$goods_a){
            $rs['code'] = 1003;
   $rs['msg'] = \PhalApi\T('信息错误');
   return $rs;
        }
  if(!is_array($goods_a)){
            $rs['code'] = 1004;
   $rs['msg'] = \PhalApi\T('信息错误');
   return $rs;
        }

foreach($goods_a as $k=>$v){

  $info=$Domain_Course->getDetaild($where);
                if(!$info){
                    $rs['code'] = 1005;
                    $rs['msg'] = \PhalApi\T('含有已下架课程');
                    return $rs;
 }

   $isbuy=$Domain_Course->getBuy($where2);
                if($isbuy){
                    $rs['code'] = 1006;
                    $rs['msg'] = \PhalApi\T('含有已购买的课程');
                    return $rs;
}

   $money+=$info['payval'];   
        }

$model = new Model_Cart();
$res=$model->addOrder($order_data);