Xero for WooCommerce

I would like to request the addition of a filter hook to allow customization of the invoice reference pieces in the Xero invoice XML output.

Location:
/includes/class-wc-xr-invoice.php – Line 420 in the to_xml() method

Current Behavior:
The invoice reference is currently hardcoded to include payment method, transaction ID, and order number, with no way to customize or override these values.

Proposed Change:
Add a filter hook that allows developers to modify the $reference_pieces array before it’s compiled into the XML reference field:

$reference_pieces = apply_filters( ‘woocommerce_xero_invoice_reference_pieces’, $reference_pieces, $order, $this );

Use Case:

This would allow merchants to use custom reference formats (such as purchase order numbers) in their Xero invoices without modifying the plugin directly.

Example Usage:

add_filter( ‘woocommerce_xero_invoice_reference_pieces’, function( $reference_pieces, $order, $invoice ) {
$po_number = get_post_meta( $order->get_id(), ‘purchase_order_number’, true );
if ( ! empty( $po_number ) ) {
$reference_pieces = array( esc_xml( $po_number ) );
}
return $reference_pieces;
}, 10, 3 );

This is a non-breaking change that maintains backward compatibility while providing extensibility for custom implementations.