shopping cart class with add/edit/delete product functionality.

Shopping Cart Class                  

This module is a shopping cart class with add/edit/delete product functionality.
Each item is stored in a session variable as an array with the productID being the key
and the quantitly of the item as the value. The cookie stores the serialized cart contents
between visits.
IMPORTANT NOTE: The show_cart function
outputs a very bland table so you will need to edit this to beautify it.

<?php class cart {         /**     * The expiry time for the cart cookie     */     var $expire = 3600;             var $del_cookie = -1;         /**     * Class constructor     *     * Start the session, if the cart doesn't exist as a session variable, check for a cookie,     * if the cookie isn't there, make a new cart.     */     function cart()     {     // Start the session.     session_start();         $time = time();     $this->expire = $time + $this->expire;         // If the session variables haven't been registered yet, do that now.     if(!isset($_SESSION['cart']))         {                 if(isset($_COOKIE['cart']))             {             $_SESSION['cart'] = array();             $_SESSION['cart'] = unserialize(stripslashes($_COOKIE['cart']));             $_SESSION['total_items'] = $this->cart_calculate_items($_SESSION['cart']);             $_SESSION['total_price'] = $this->cart_calculate_price($_SESSION['cart']);             }         else             {             $_SESSION['cart'] = array();             $_SESSION['total_items'] = 0;             $_SESSION['total_price'] = 0.00;                         $s_cart = serialize($_SESSION['cart']);             setcookie('cart', $s_cart, $this->expire);             }         }         }                 /**     * Displays the cart     *     * @param array $cart The cart you want to display.     * @param boolean $pictures Show pictures in cart? (default=false)     * @param boolean $editable Is cart editable? (default=true)     */     function cart_show($cart, $pictures = 'false', $editable = 'true')     {     require($_SERVER['DOCUMENT_ROOT'].'/path/to/database/connection_code.php');     mysql_select_db($database_connAT, $connAT);     echo "<table border=\"1\"><tr><td>Product</td><td>Quantity</td><td>Price</td></tr>\n";     foreach($cart as $productID => $qty)         {         $product = $this->cart_get_item_details($productID);         echo "<tr>\n";         echo "<td>".$product['details']."</td><td>".$qty."</td><td>£".$product['price']."</td>\n";         echo "</tr>\n";         }     echo '</table>';     }             /**     * Adds an item to the cart.     *     * If the item is already in the cart, it increments the quantity by one.     * Otherwise, it adds one of the selected item to the cart. It then recalculates     * the number of items in the cart and the total cost.     *     * @param string $item The productID to be added.     */     function cart_add_item($item)     {     // If cart item exists, increment it by one...     if(isset($_SESSION['cart'][$item]))         {         $_SESSION['cart'][$item]++;                 }             // ...otherwise add it as a new item.     else         {         $_SESSION['cart'][$item] = 1;         }         // Recalculate totals     $_SESSION['total_items'] = $this->cart_calculate_items($_SESSION['cart']);     $_SESSION['total_price'] = $this->cart_calculate_price($_SESSION['cart']);     $s_cart = serialize($_SESSION['cart']);     setcookie('cart', $s_cart, $this->expire);     }             /**     * Removes a product from the cart.     *     * Removes a product totally from the cart by unsetting it's key and value     * from the session array.     */     function cart_delete_item($productID)     {     // Unset product variable     unset($_SESSION['cart'][$productID]);         // Recalculate totals     $_SESSION['total_items'] = $this->cart_calculate_items($_SESSION['cart']);     $_SESSION['total_price'] = $this->cart_calculate_price($_SESSION['cart']);     $s_cart = serialize($_SESSION['cart']);     setcookie('cart', $s_cart, $this->expire);     }         /**     * Edits the number of each item in the cart     *     * If the number is set to zero, remove the item by unsetting the session variable. If     * the number is anything else, set it the that number.     *     * @todo I'm not sure if this function needs any parameters passed to it to work     * so if it doesn't, this could be why.     */     function cart_edit_item()     {     // Make sure the variables are being POSTed     if(isset($_POST['update']))         {         foreach($_SESSION['cart'] as $productID => $qty)             {             if($_POST['$productID'] ==  0)                 {                 unset($_SESSION['cart'][$productID]);                 }             else                 {                 $_SESSION['cart'][$productID] = $_POST['productID'];                 }             }         }     // Recalculate totals     $_SESSION['total_items'] = $this->cart_calculate_items($_SESSION['cart']);     $_SESSION['total_price'] = $this->cart_calculate_price($_SESSION['cart']);     $s_cart = serialize($_SESSION['cart']);     setcookie('cart', $s_cart, $this->expire);     }                 /**     * Calculates the number of items in the cart.     *     * Calculates the number of items in the cart by looping through the cart incrementing     * the number of items for each product.     *     * @param array $cart The cart to count items in.     * @return integer The number of items in the cart.     */     function cart_calculate_items($cart)     {     // Initialise variable to default value     $items = 0;         // Make sure the cart is actully an array!     if(is_array($cart))         {         // Loop through the cart and add the quanity of each item the the total         foreach($_SESSION['cart'] as $productID => $qty)             {             $items += $qty;             }         }     // Return the total number of items     return $items;     }                 /**     * Calculates the total price of the cart contents.     *     * This function is one of the slowest in this application     * as it has a long database query to carry out and total up.     *     * @param array $cart The cart to total the price in.     * @return float The total price of cart contents.     */     function cart_calculate_price($cart)     {     // Initialise variable to default value     $price = 0.00;         // Make sure the cart is actully an array!     if(is_array($cart))         {                 /**         * Require the database connection for finding prices.         */         require($_SERVER['DOCUMENT_ROOT'].'/path/to/database/connection_code.php');         mysql_select_db($database_connAT, $connAT);                 // Loop through the cart array matching prices to products         foreach($cart as $productID => $qty)             {             $query = "SELECT price FROM stock WHERE productID='$productID'";             $result = mysql_query($query);                         // Then adding the (item price * quantity) to the total price             //  and starting the loop again             if($result)                 {                 $row_result = mysql_fetch_assoc($result);                 $item_price = $row_result['price'];                 $price += $item_price*$qty;                 }             }         }     // Return the total price     return $price;     }             function cart_get_item_details($productID)         {         $query = "SELECT * FROM stock WHERE productID='$productID'";         $result = mysql_query($query);         $row_result = mysql_fetch_assoc($result);         return $row_result;         }     } // Ussage Example $cart = new cart(); // Add product number 250 cart_add_item(250); // show the contents cart_show($_SESSION['cart']); // Remove product number 250 cart_delete_item(250); ?>