WC 2.2 payment gateways: Adding refund support and transaction IDs

Payment Gateways in WC 2.2 can be improved with the introduction of two new features; being able to store a transaction ID in a standardised format, and being able to programatically handle refunds.

Storing transaction IDs

Storing transaction IDs is useful because these will appear in the order interface:

If your gateway makes use of the $order->payment_complete() method, storing your transaction ID is a simple process. Simply pass the transaction ID to the method:

$order->payment_complete( $transaction_id );

WooCommerce will then store the ID as post meta.

If you need to do this manually for any reason, you can set it directly using add_post_meta:

add_post_meta( $order->id, '_transaction_id', $transaction_id, true );

Turning the transaction ID into a link

You’ll notice in the screenshot above, the transaction ID is a link – in this case linking the the transaction on the PayPal site. If you want to do this for your gateway, in your constructor set a “view_transaction_url” property, e.g:

$this->view_transaction_url = 'https://www.paypal.com/cgi-bin/webscr?cmd=_view-a-trans&id=%s';

WooCommerce will substitute the %s for the transaction ID during output.

Supporting refunds

To support refunds you need to create a process_refund() method in your gateway class. Without showing the refund code itself (which you’ll be writing) your method should look something like:

public function process_refund( $order_id, $amount = null ) {
  // Do your refund here. Refund $amount for the order with ID $order_id
  return true;
}

This method should return a bool (true or false, if the refund was successfull or unsuccessfull) or a WP_Error object if something went wrong.

As well as created this method, you need to define support for refunds. To do this, set the “supports” property in your constructor, e.g.:

$this->supports = array(
  'products',
  'refunds'
);

This will let WooCommerce know that your gateway can handle refunds.