How do I edit a product attribute using PHP during a cart checkout in Magento?

I have a two part question about customizing my Magento store.

When someone buys a downloadable product, I want to generate a licence code and include it in the invoice.

I have added a product attribute called ‘license_code’ to my product’s default attribute set and I want to set its value with php when a customer checks out.

What is the event to observe that will let me access the products in the cart just after they are purchased but before the invoice is created?

I also need to know what script to use to set a product’s attribute value during that event.

Thank you for your help!

2 thoughts on “How do I edit a product attribute using PHP during a cart checkout in Magento?”

  1. Possible events are sales_order_place_before or sales_convert_quote_*.

    You cannot save your ‘license_code’ attribute because that will affect all products, a product does not store it’s values when ordered. Instead a better idea would be to manipulate the options of an order item.

    function salesConvertQuoteItemToOrderItem(Varien_Event_Observer $observer)
        $orderItem = $observer->getOrderItem();
        $options = $orderItem->getProductOptions();
        $options['licence_code'] = YOUR-DOWNLOADABLE-CODE-HERE;

    Retrieving the code later is essentially the same process with getProductOptions(), the order item objects are already used on the order view pages so are easy to find and use in your theme.

  2. Ok I think I got it figured out.

    I set up my event observers as follows:


    and then my observing function as:

    public function generate_licenses($observer)
        $orderItem = $observer->getEvent()->getItem();
        $options = $orderItem->getProductOptions();
        $options['licence_code'] = 'YOUR-DOWNLOADABLE-CODE-HERE';
      return $this;

    Thank you so much for the help, clockworkgeek!

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