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我正在创建一个有四个按钮的购物车继续购物、清除购物车、更新购物车和下订单

 undefined index cart

但是购物车来自会话，当我按下清除购物车按钮时

it unsets the session of cart

那么我在哪里做错了？谁能帮忙？这是我的代码

<?php
    include("includes/db.php");
    include("includes/functions.php");

    if($_REQUEST['command']=='delete' && $_REQUEST['pid']>0){
        remove_product($_REQUEST['pid']);
    }
    else if($_REQUEST['command']=='clear'){
        unset($_SESSION['cart']);
    }
    else if($_REQUEST['command']=='update'){
        $max=count($_SESSION['cart']);
        for($i=0;$i<$max;$i++){
            $pid=$_SESSION['cart'][$i]['productid'];
            $q=intval($_REQUEST['product'.$pid]);
            if($q>0 && $q<=999){
                $_SESSION['cart'][$i]['qty']=$q;

            }
            else{
                $msg='Some proudcts not updated!, quantity must be a number between 1 and 999';
            }
        }
    }

?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Shopping Cart</title>
<script language="javascript">
    function del(pid){
        if(confirm('Do you really mean to delete this item')){
            document.form1.pid.value=pid;
            document.form1.command.value='delete';
            document.form1.submit();
        }
    }
    function clear_cart(){
        if(confirm('This will empty your shopping cart, continue?')){
            document.form1.command.value='clear';
            document.form1.submit();
        }
    }
    function update_cart(){
        document.form1.command.value='update';
        document.form1.submit();
    }


</script>
</head>

<body>
<form name="form1" method="post">
<input type="hidden" name="pid" />
<input type="hidden" name="command" />
    <div style="margin:0px auto; width:600px;" >
    <div style="padding-bottom:10px">
        <h1 align="center">Your Shopping Cart</h1>
    <input type="button" value="Continue Shopping" onclick="window.location='products.php'" />
    </div>
        <div style="color:#F00"><?php echo'' ;?></div>
        <table border="0" cellpadding="5px" cellspacing="1px" style="font-family:Verdana, Geneva, sans-serif; font-size:11px; background-color:#E1E1E1" width="100%">
        <?php
            if(is_array($_SESSION['cart'])){
                echo '<tr bgcolor="#FFFFFF" style="font-weight:bold"><td>Serial</td><td>Name</td><td>Price</td><td>Qty</td><td>Amount</td><td>Options</td></tr>';
                $max=count($_SESSION['cart']);
                for($i=0;$i<$max;$i++){
                    $pid=$_SESSION['cart'][$i]['productid'];
                    $q=$_SESSION['cart'][$i]['qty'];
                    $pname=get_product_name($pid);
                    if($q==0) continue;
            ?>
                    <tr bgcolor="#FFFFFF"><td><?php echo $i+1?></td><td><?php echo $pname?></td>
                    <td>$ <?php echo get_price($pid)?></td>
                    <td><input type="text" name="product<?php echo $pid?>" value="<?php echo $q?>" maxlength="3" size="2" /></td>                    
                    <td>$ <?php echo get_price($pid)*$q?></td>
                    <td><a href="javascript:del(<?php echo $pid?>)">Remove</a></td></tr>
            <?php                   
                }
            ?>
                <tr><td><b>Order Total: $<?php echo get_order_total()?></b></td><td colspan="5" align="right"><input type="button" value="Clear Cart" onclick="clear_cart()"><input type="button" value="Update Cart" onclick="update_cart()"><input type="button" value="Place Order" onclick="window.location='billing.php'"></td></tr>
            <?php
            }
            else{
                echo "<tr bgColor='#FFFFFF'><td>There are no items in your shopping cart!</td>";
            }
        ?>
        </table>
    </div>
</form>
</body>
</html>
4

3 回答 3

1

如果您还没有开始填充您的购物车，那么该元素将是未定义的。在处理数组元素时，最好添加额外的测试 array_key_exists()。但是，在您的情况下，问题更多在于您通常处理数组的方式。

PHP 非常宽容，因此您必须在编码方式上执行自己的纪律。一个值得使用的非常好的做法是在开始使用变量之前显式初始化变量。

// somewhere near the top of your code
$_SESSION['cart'] = array_key_exists('cart', $_SESSION)?$_SESSION['cart']:array();

并且不要在清除测试中取消设置它......只需将其设置回一个空数组。

else if($_REQUEST['command']=='clear'){
    $_SESSION['cart'] = array();
}
于 2013-03-23T07:43:21.263 回答
0

这是简单的 PHP 购物车教程 

$product_id = $_GET['id']; //the product id from the URL 
$action = $_GET['action']; //the action from the URL 

//if there is an product_id and that product_id doesn't exist display an error message
if($product_id && !productExists($product_id)) {
    die("Error. Product Doesn't Exist");
}

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

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

    case "remove":
        $_SESSION['cart'][$product_id]--; //remove one from the quantity of the product with id $product_id 
        if($_SESSION['cart'][$product_id] == 0) unset($_SESSION['cart'][$product_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;

}

?>

从这里

于 2013-03-23T07:17:17.807 回答
0 
switch($action) { //decide what to do 

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

    case "remove":
        $_SESSION['cart'][$product_id]--; //remove one from the quantity of the product with id $product_id 
        if($_SESSION['cart'][$product_id] == 0) unset($_SESSION['cart'][$product_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;
于 2013-05-21T02:03:09.673 回答