Run custom logic when order creation is rolled back due to an exception

Question

I'm building a module that integrates 3rd party gift cards. I'm using an observer before the order is placed to charge the card.

public function beforeOrderPlace($observer)
{
    $order = $observer->getOrder();
    $this->chargeGiftcard($order->getGiftcardNumber(), $order->getGiftcardAmount());
}

However, in the event the order can't be created (i.e. the remaining balance charged to a credit card failed) I need to "uncharge" the giftcard from the 3rd party, with something like

public function rollback($observer)
{
    $order = $observer->getOrder();
    $this->addBalanceToGiftcard($order->getGiftcardNumber(), $order->getGiftcardAmount());
}

How can I hook into the transaction used during order creation to add my rollback?

Answer 1

I would hook the observer to the invoice create event so you're sure everything went well. When a CC payment is cleared it will create an invoice in Magento.

Next to that you'll need to do a giftcard refund when a creditmemo is created. As with any Payment method there are a dozen more checks I can think of you might want to do to prevent overcharging or fraud. Did you take a look at any of the existing giftcard modules out there to see how they approached the issue?

Check out this list of events to find a good one to hook https://www.nicksays.co.uk/magento-events-cheat-sheet-1-7/