使用会话将项目添加到购物篮答案

【问题标题】：Adding items to shopping basket using sessions使用会话将项目添加到购物篮
【发布时间】：2014-05-17 12:08:25
【问题描述】：

这是一个购物篮，用户可以单击添加到购物篮，传递一个 action=add 变量，这是从 switch 语句中选择的。但是，第一次添加项目时会导致错误（底部）。这只是第一次发生，这让我相信这是因为 session[cart] 尚未创建。

变量设置在这里：

if(isset($_GET['id'])) 
{
$Item_ID = $_GET['id'];//the product id from the URL 
$action = $_GET['action'];//the action from the URL 
} 
else
{
$action = "nothing";
}




<?php

if(empty($_SESSION['User_loggedin']))
{ 
header ('Location: logon.php');
}
else
{

switch($action) { //decide what to do 

    case "add":
        $_SESSION['cart'][$Item_ID]++; //add one to the quantity of the product with id $product_id 
    break;

    case "remove":
        $_SESSION['cart'][$Item_ID]--; //remove one from the quantity of the product with id $product_id 
        if($_SESSION['cart'][$Item_ID] == 0) unset($_SESSION['cart'][$Item_ID]); //if the quantity is zero, remove it completely (using the 'unset' function) - otherwise is will show zero, then -1, -2 etc when the user keeps removing items. 
    break;

    case "empty":
        unset($_SESSION['cart']); //unset the whole cart, i.e. empty the cart. 
    break;

    case "nothing":
    break;
}

if(empty($_SESSION['cart']))
{ 
echo "You have no items in your shopping cart.";
}

添加项目工作正常，但是当我第一次向空篮子添加东西时，我收到以下错误：

Notice: Undefined index: cart in H:\STUDENT\S0190204\GGJ\Basket.php on line 57 Notice: Undefined index: 1 in H:\STUDENT\S0190204\GGJ\Basket.php on line 57

【问题讨论】：

到目前为止的答案没有运气：/

标签： php

【解决方案1】：

这是因为您的 $_SESSION['cart'] 变量未针对第一个请求进行初始化。试试下面的东西。

if(empty($_SESSION['User_loggedin']))
{ 
header ('Location: logon.php');
}
else
{

   // Added this...
   if(empty($_SESSION['cart'])){
       $_SESSION['cart'] = array();
   }

switch($action) { //decide what to do 

    case "add":
        $_SESSION['cart'][$Item_ID]++; //add one to the quantity of the product with id $product_id 
    break;

    case "remove":
        $_SESSION['cart'][$Item_ID]--; //remove one from the quantity of the product with id $product_id 
        if($_SESSION['cart'][$Item_ID] == 0) unset($_SESSION['cart'][$Item_ID]); //if the quantity is zero, remove it completely (using the 'unset' function) - otherwise is will show zero, then -1, -2 etc when the user keeps removing items. 
    break;

    case "empty":
        unset($_SESSION['cart']); //unset the whole cart, i.e. empty the cart. 
    break;

    case "nothing":
    break;
}

if(empty($_SESSION['cart']))
{ 
echo "You have no items in your shopping cart.";
}

【讨论】：

【解决方案2】：

如果你认为你没有创建 $_SESSION['cart'] 变量，你可以简单地检查一下

if (!isset($_SESSION['cart']))
{
    //Initialize variable
}

此伪代码将检查变量是否未设置，然后执行一些后续代码
（例如$_SESSION['cart'] = array();）。

【讨论】：