如何在prestashop中为用户更改购物车？

我需要创建一个链接，更改用户的购物车与过期的购物车

这是我试过的，但不起作用

<?php
if (!defined('_PS_ADMIN_DIR_'))
    define('_PS_ADMIN_DIR_', (getcwd().'/../../') );//prima del require_once
require_once(dirname(__FILE__).'/../../config/config.inc.php');

...

$this->context->cookie->id_cart = 6;
$this->context->cart = new Cart(6);
$this->context->cookie->write();
$this->context->cookie->update();
Tools::redirect('index.php?controller=order');

---

怎么样：$this->context->cart->id=6