Altering Orders.php to insert (sub)category into invoice line item details

Hi, I'm hoping someone can help me with a small coding problem I'm having.

I'm trying to make the order page display the category of the item instead of the product model (which is useless to me due to the way my custom mass populator program works) - I've identified the relevent piece of code that needs changing in orders.php as:

      echo '            </td>' . "\n" .
           '            <td class="dataTableContent" valign="top">' . $order->products[$i]['model'] . '</td>' . "\n" .
           '            <td class="dataTableContent" align="right" valign="top">' . 

So products model needs to be replaced with category. Does anyone know how to do this? Also, bonus question, the category will be a subcategory, so is that different?

Thanks in advance.

You could try using the function zen_get_categories_name_from_product by passing the products_id to it ...

How would I do that? Sorry, I'm fairly new to PHP.

As an example, this code uses both model and the specific categories_name for the Product:

           '            <td class="dataTableContent" valign="top">' . $order->products[$i]['model'][B] . '<br>' . zen_get_categories_name_from_product($order->products[$i]['id'])[/B] . '</td>' . "\n" .

That is brilliant. Works perfectly, thanks very much!