无法让 OOP 正常工作 - 购物车、PHP

Question

我似乎在这个购物车中找不到任何故障，但它显示不正确。我看到了这个 YouTube 视频，并尝试了那里的代码 (https://www.youtube.com/watch?v=SlwMBtx0YMQ)，但它使用的是 MySQL 而不是 MYSQL PDO;所以我改为转换为 PDO。我正在从另一个页面呼应该类以显示 HTML 代码。是的，我是新手..

代码从挪威语翻译成英语：

<?php
    class shoppingCart {
        // This function works as it should it seems like
        function writeShoppingCart() {
            $cart = $_SESSION["cart"];
            if (!$cart) {
                return "0 products";
            } else {
                $products = explode(",",$cart);
                $number = (count($products) > 1) ? "s" : "";
                return "<a href='cart.php'>".count($products)." Products ".$number."";
            }
        }
        // But this function is not working as it should (?)
        function showCart() {
            $cart = $_SESSION["cart"];
            if ($cart) {
                $products = explode(",",$cart);
                $content = array();
                // FAULT HERE MAYBE ?
                foreach ($products as $product) {
                    $content[$product] = (isset($content[$product])) ? $content[$product]+1 : 1;
                }
                $output[] = '<form action="cart.php?action=update" method="POST" id="cart"';
                $output[] = '<table>'; // This was corrected by "jeyoung" (">")
                // HERE ? $content .. I THINK
                foreach ($content as $productID=>$qty) {
                    $sql = "SELECT * FROM Product WHERE ProductID = ".productID;
                    // FAULT HERE ....?
                    echo " WORKS HERE 1 "; // From here and down the code stops displaying ...
                    $result = $conn->query($sql);
                    echo " WORKS HERE 2 "; // This is just check-marks to make it easier to find the fault ..
                    $user_data = $result->fetch(PDO::FETCH_BOTH);
                    echo " WORKS HERE 3 ";
                    extract($user_data);

                    $output[] = '<tr>';
                    $output[] = '<td><a href="cart.php?action=delete&id='.$productID.'" > Delete </a></td>';
                    $output[] = '<td>'.$productName.'</td>';
                    $output[] = '<td>NOK '.$PriceNOK.',-</td>';
                    $output[] = '<td><input type="text" name="qty'.$productID.'" value='.$qty.' size="3" maxlength="3" /></td>';
                    $output[] = '<td> NOK '.($PriceNOK * $qty).',-</td>';
                    $totalCost += $PriceNOK * $qty;
                    $output[] = '</tr>';
                    echo " WORKS HERE 4 ";
                }
                $output[] = '</table>';
                $output[] = '<p> Total: <strong>NOK '.$totalCost.',-</strong></p>'; // NOK = Norwegian Kroner (currency)
                $output[] = '<button type="submit">Update Cart</button>';
                $output[] = '</form>';
            } else {
                $output[] = '<p>Cart is empty.</p>'; // Cart empty
        }
            return join('',$output);
        }
    }
    ?>

Answer 1

你的函数有错误

    function showCart() {
        $cart = $_SESSION["cart"];
        if ($cart) {
            $output = explode(",",$cart);
            $content = array();
            // FAULT HERE MAYBE ?
            foreach ($products as $product) {

您的foreach 使用了$products，但您没有此变量。您需要按照在第一个函数中的方式分配该变量。而不是

$output = explode(",",$cart);

使用

$products = explode(",",$cart);

代码开头的“s”不是拼写错误，如果需要，应该将产品更改为产品。

Answer 2

在这一行，$produksjon[] = '<table';，标签没有正确关闭。

应该是$produksjon[] = '<table>';。

Answer 3

我忘记在 ShoppingCart 类本身中定义 $conn。我只是在外面定义的！不知道这是必要的。