$ _SERVER [ 'REQUEST_METHOD'] = 'POST';不工作

Question

它没有进入if( $_SERVER['REQUEST_METHOD']=='POST')所以我试过了  $_SERVER['REQUEST_METHOD']='POST'仍显示错误

  

注意：C：\ Abyss Web Server \ htdocs \ new 1.php中的未定义索引：qty   第9行

     

警告：在C：\ Abyss Web中为foreach（）提供的参数无效   第9行的Server \ htdocs \ new 1.php

注意：第22行的C：\ Abyss Web Server \ htdocs \ new 1.php中的数组到字符串转换

session_start();
if(!isset($_SESSION['user_id'])){
    require('login_tools.php');
    load();
}
$_SERVER['REQUEST_METHOD']='POST';
if($_SERVER['REQUEST_METHOD']=='POST'){
        foreach($_POST['qty'] as $item_id => $item_qty){
            $id=(int)$item_id;
            $qty=(int)$item_qty;
            if($qty == 0){
                unset($_SESSION['cart'][$id]);
            }elseif($qty >0){
                $_SESSION['cart'][$id]['quantity']=$qty;
            }
        }
        $total=0;$e=array();
        if(!empty($_SESSION['cart'])){
            require('connectDB.php');

            $q="SELECT * FROM shop WHERE item_id IN ";
            foreach($_SESSION['cart'] as $id =>$value){
                $q.=$id.',';
            }
            $q=substr($e,0,-1); " )ORDER BY item_id ASC";
            $r=mysqli_query($dbc,$q);



        }else{
            $err[]="your cart is currently empty";
        }
}
?>