Shopping Cart $_SESSION Problem

问题

I am working on a basic shopping cart. However, it appears as though the $_SESSION variable is not properly being stored or accessed. For instance if you travel to here it will display the item name. But on refresh to cart.php without any $_GET variables it returns nothing. What am I doing wrong?

<?php
include "tickets/config.php";

if (isset ($_GET['action']) && isset($_GET['item'])) {
    $cart = new Cart($_GET['item']);
    if ($_GET['action'] == "addItem") {
        $cart->addItem();
        $cart->get_items_code();
        $cart->populate();
    }
    if($_GET['action'] == "removeItem") {
        $cart->removeItem();
        $cart->get_items_code();
        $cart->populate();
    }
    $cart->postAllItems();
}
else {
    $cart = new Cart(null);
    $cart->get_items_code();
    $cart->populate();
    $cart->postAllItems();
}

class Cart {
    protected $all_items = array();
    protected $request_item;
    protected $content;
    protected $item_obj;

    public function __construct($request_item) {
        $this->request_item = $request_item;
        if ($this->request_item) 
            $this->item_obj = new Item($this->request_item);
        $this->all_items = $this->getAllItems();
    }

    public function getAllItems() {
        if ($_SESSION['cart'])
            $request = $_SESSION['cart'];
        else
            $request = array();
        return $request;
    }

    public function postAllItems() {
        $_SESSION['cart'] = $this->all_items;
    }

    public function addItem () {
        array_push($this->all_items, $this->item_obj);
    }

    public function removeItem() {
        unset($this->all_items[$this->item_obj->get_item()]);
    }

    public function get_items_code() {

        //for($i = 0; $this->all_items[$i]; $i++) {
        foreach($this->all_items as $item) {
            $name = $item->get_name();
            $this->content .= <<<HTML
<div class="item">
$name
</div>      
HTML;
        }
    }

    public function populate() {
        echo <<<HTML
<div id="list">     
$this->content
<div>
HTML;
    }
}


class Item {
    protected $id;
    protected $name;
    protected $price;
    protected $desc;
    protected $colors;
    protected $sizes;
    protected $pic_url;
    protected $all_info;

    public function __construct($id) {
        $this->id = $id;
        $this->get_item_info();
    }

    public function get_item() {
        return ($this);
    }

    public function get_name() {
        return $this->name;
    }

    protected function get_item_info() {
        $sql = "SELECT * FROM catalog WHERE id = ".$this->id;
        $this->all_info = mysql_query($sql);
        $this->all_info = mysql_fetch_array($this->all_info);
        $this->name = $this->all_info['name'];
        $this->price = $this->all_info['price'];
        $this->desc = $this->all_info['description'];
        $this->colors = $this->all_info['colors'];
        $this->sizes = $this->all_info['sizes'];
        $this->pic_url = $this->all_info['picture'];
    }

}




?>

回答1:

You need to initialize the session using the session_start()-function at the top of the page (before the contents of the sessions are modified or read).

回答2:

Your code looks fine, but you must call session_start() on every page that modifies the session or reads from the session. Just putting it at the top of the page will work.

session_start();

回答3:

I also recently had a problem with $_SESSION vars maintaining themselves after page redirects, which could be your problem.

Session variables will not survive a redirect from a http://www.example.com to a http://example.com redirect. So, you use redirects with relative or absolute paths, but do it without the sitename:

use

header('Location: /new_page.php');

as opposed to

header('Location: http://www.exmple.com/new_page.php')

Maybe doesn't apply here, but did trip me up quite a bit.

来源：https://stackoverflow.com/questions/4820443/shopping-cart-session-problem

标签

php

shopping-cart