Php 设计Html5驱动的购物车？？

我正在开发一个移动购物车，我正在学习本教程，

http://go.developer.ebay.com/devzone/articles/building-html5-powered-shopping-cart-ios-part-1

在本教程中，我将产品作为Json转换为Html。要使用以下代码将产品获取为Json iam

    <?php

// simulates result of db query for categories
$categories = array();
$categories[] = array(id => 1, parent_id => 0, name => 'root');
$categories[] = array(id => 2, parent_id => 1, name => 'Compact Discs');
$categories[] = array(id => 3, parent_id => 1, name => 'Concert Souvenirs');

// simulates result of db query for products
$products = array();
$products[] = array(id => 1, category_id => 2, sku => 'CD001', price=>15.00, name => 'CD: Greatest Hits');
$products[] = array(id => 2, category_id => 2, sku => 'CD002', price=>15.00, name => 'CD: Unplugged');
$products[] = array(id => 3, category_id => 2, sku => 'CD003', price=>15.00, name => 'CD: World Tour');
$products[] = array(id => 4, category_id => 3, sku => 'PD001', price=>10.00, name => 'Souvenir Pin');
$products[] = array(id => 5, category_id => 3, sku => 'PD002', price=>10.00, name => 'Mug');
$products[] = array(id => 6, category_id => 3, sku => 'PD003', price=>20.00, name => 'Hat');
$products[] = array(id => 7, category_id => 3, sku => 'PD004', price=>12.00, name => 'Summer Tour Poster');
$products[] = array(id => 8, category_id => 3, sku => 'PD005', price=>5.00,  name => 'Concert Program');
?>

如果我运行catalog.php，我会得到Json输出，但会有错误，比如所有行上都有未定义的常量。 按照上述教程的指导，我无法创建任何表格。但是，当我访问索引文件时，我得到了一个空白屏幕。

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请帮助我获取输出。

您必须在php中引用字符串数组键，否则将收到有关未定义常量的警告

$categories[] = array('id' => 2, 'parent_id' => 1, 'name' => 'Compact Discs');

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如果您将收到的实际错误消息包括在内，这将非常有用。