Trying to build an AJAX cart in Magento, configuration options not showing - ajax

Question

PROBLEM:
I'm trying to build an AJAX cart in magento, but I can't seem to fetch the chosen configuration option(s) of configurable products. I believe am invoking the the right method ($this->getOptionList()) to get them. It should return an array with options and labels, but it returns nothing!! To be clear, they are showing up in the normal cart.
EXPLANATION:
The short story of how I'm doing it:
I use the Cart Controller of the Mage_Checkout module, but I change the template to something very minimal (using layout updates in the current theme), and a custom module with a router defined in it.
Long story:
I have created a module MyNameSpace_Checkout in which I have defined a router that binds the frontName 'ajaxcart' to the controllers in the Mage_Checkout module.
Now in the local.xml file of my current theme I put the following layout updates under the 'ajaxcart_cart_index' handle:
<ajaxcart_cart_index>
<reference name="root">
<action method="setTemplate">
<template>ajaxcart/cart/index.phtml</template>
</action>
<block type="checkout/cart" name="checkout.cart" template="ajaxcart/cart/show.phtml" as="cart"></block>
</reference>
</ajaxcart_cart_index>
My template ('ajaxcart/cart/show.phtml') is being used, so this worked pretty well. I tested it when I went to http://domain.com/ajaxcart/cart
index.phtml:
<?php echo $this->getChildHtml('cart'); ?>
show.phtml:
<?php foreach($this->getItems() as $_item): ?>
<?php $_renderer = $this->getItemRenderer($_item->getProductType())->setItem($_item); ?>
<?php /* render an item */ ?>
<?php endforeach; ?>
Seeing as $this in this context refers to the Cart Block of the Mage_Checkout module, and digging around in the method getItemHtml() of this class (its superclass actually) I found that the block object per item in the cart is retrieved using the second line in the show.phtml sample above ($_renderer).
Does anyone know why information is missing? The whole reason I'm using the original controller is that it is probably doing some essential stuff, but it's still not working!!
Thanks in advance.

Answer 1

I found the problem myself, the layout updates (local.xml of the current theme) were the problem:
<action method="addItemRender">
<type>configurable</type>
<block>checkout/cart_item_renderer_configurable</block>
<template>checkout/cart/item/default.phtml</template>
</action>
I took another look at checkout.xml of the base/default theme and it sported some addItemRender (layout xml) methods in the cart/checkout block under the checkout_cart_index handle. Specifically for my problem, the above element was missing and that messed up the rendering of a configurable product item in the cart. A special type of block object needs to be loaded that actually has the (PHP) method getOptionList().