Magento add custom attribute to transaction email items

Question

I want to change the default SKU field inside the transactional email item field, to a custom attribute.

Therefore I need to edit the following file:

/app/design/frontend/theme/theme/template/email/order/items/order/default.phtml

I want to change the following value:

<?php echo $this->escapeHtml($this->getSku($_item)) ?>

My custom attribute value is "dpn" and it is named "DPN".

How can I change this?

I tried the following but that does not work:

<?php echo $this->escapeHtml($this->getDpn($_item)) ?>

Answer 1

You need to understand that calling $this->getSku() or $this->getDpn() is referring to a method that you can/could find in the related Block, in your case:

app\code\core\Mage\Sales\Block\Order\Email\Items\Default.php

in which you'll find the relevant getSku() method. You could in turn extend this class and add your getDpn() method, but I believe what you are trying to do it get a product's attribute.

If it's the case, you only have to do

<?php echo $this->escapeHtml($_item->getProduct()->getDpn()) ?>

But be aware that it might be costly because Magento will internally call app\code\core\Mage\Sales\Model\Order\Item.php:getProduct() which instantiates the given product.