$Product does not hold categories, why not

-- HikaShop version -- : 2.5.0
-- Joomla version -- : 3.1
-- PHP version -- : 5.4.3
-- Browser(s) name and version -- : Chrome
-- Error-message(debug-mod must be tuned on) -- : $product variable does not print the categories.

Hi,
I am following the documentation here on the $Product variable, and I need to access the categories array. When I print the $Product variable I can see that the categories are not in the array. Nothing at all, not even an empty categories array.
My product all have categories, how or where do I get access to those product categories? I'm working on a shipping plugin.
Thanks!

doc link:
www.hikashop.com/support/documentation/157

Hi Jerome,
That sounds like my issue. I am just doing a print_r($product) inside a function I passed the $order variable to. I didn't do a full load.
I'll try this below....from the docs website.....Thank you very much.

If you want to load the whole information of an order, you can use the code :
$orderClass = hikashop_get('class.order');
$order = $orderClass->loadFullOrder($order_id, true, false);
Similarly to the cart, the products will be available in the attribute as an array of product objects:
$order->products

I am trying to access those categories from a shipping plugin that extends the hikashopshipping plugin.
How can I access it from there?
It is needed in the onShippingDisplay function.

Thanks.

I think i got it. This has been an invaluable exercise in understanding Hikashop.

$productClass = hikashop_get('class.product');
$product=$productClass->getCategories(79);

This returns an array. Pretty cool, now I know how to access the other classes and their functions.