cart.php

完善的PHP/MySQL电子商务方案

<?
/* cart.php (c) 2000 Ying Zhang ([e-mail])
 *
 * TERMS OF USAGE:
 * This file was written and developed by Ying Zhang ([e-mail])
 * for educational and demonstration purposes only.  You are hereby granted the
 * rights to use, modify, and redistribute this file as you like.  The only
 * requirement is that you must retain this notice, without modifications, at
 * the top of your source code.  No warranties or guarantees are expressed or
 * implied. DO NOT use this code in a production environment without
 * understanding the limitations and weaknesses pretaining to or caused by the
 * use of these scripts, directly or indirectly. USE AT YOUR OWN RISK!
 */

class Cart {
	var $items;		/* array of items */
	var $total;		/* total of the cart */

	function Cart() {
	/* object constructor */

		$this->init();
	}

	function init() {
	/* this function is called to initialize (and reset) a shopping cart */

		$this->items = array();
		$this->total = 0;
	}

	function add(&$productid, $qty) {
	/* add an item to the shopping cart and update the total price */

		if (isset($productid)) {
			setdefault($this->items[$productid], 0);
			$this->items[$productid] += $qty;
		}
	}

	function set(&$productid, $qty) {
	/* set the quantity of a product in the cart to a specified value */

		if (isset($productid)) {
			$this->items[$productid] = (int) $qty;
		}
	}

	function remove(&$productid) {
	/* this function will remove a given product from the cart */

		if (isset($productid)) {
			unset($this->items[$productid]);
		}
	}

	function cleanup() {
	/* this function will clean up the cart, removing items with invalid product
	 * id's (non-numeric ones) and products with quantities less than 1 */

		foreach ($this->items as $productid => $qty) {
			if ($qty < 1) {
				unset($this->items[$productid]);
			}
		}
	}

	function itemcount() {
	/* returns the number of individual items in the shopping cart (note, this
	 * takes into account the quantities of the items as well) */

		$count = 0;
		foreach ($this->items as $productid => $qty) {
			$count += $qty;
		}

		return $count;
	}

	function get_productid_list() {
	/* return a comma delimited list of all the products in the cart, this will
	 * be used for queries, eg. SELECT id, price FROM products WHERE id IN ....
     */

		$productid_list = "";

		foreach ($this->items as $productid => $qty) {
			$productid_list .= ",'" . $productid . "'";
		}

		/* need to strip off the leading comma */
		return substr($productid_list, 1);
	}

	function recalc_total() {
	/* recalculate the total for the shopping cart, we will also do some cleanup
	 * and remove invalid items from the cart.  we have to query the database to
	 * get the prices, so instead of making one query for each product in the
	 * basket, we will gather up all the ID's we are interested in and run one
	 * query to get all the products we care about (using $in_clause) */

		$this->total = 0;

		$in_clause = $this->get_productid_list();
		if (empty($in_clause)) {
			return;
		}

		$qid = db_query("SELECT id, price FROM products WHERE id IN ($in_clause)");
		while ($product = db_fetch_object($qid)) {
			$this->total += $this->items[$product->id] * $product->price;
		}
	}
}

?>