[Refer A Friend] Add customer's referral coupon to order objects returned from REST API

functions.php

<?php


add_filter( 'woocommerce_rest_prepare_shop_order_object', 'my_automatewoo_referrals_add_advocate_coupon_to_order_api', 10, 3 );

/**
 * AutomateWoo Refer A Friend - Add customer's referral coupon to order objects returned from REST API
 * 
 * Because guest customers can't be advocates only orders by registered users will have the code added.
 *
 * @param \WP_REST_Response $response
 * @param \WC_Admin_Order $order
 * @param \WP_REST_Request $request
 *
 * @return \WP_REST_Response
 */
function my_automatewoo_referrals_add_advocate_coupon_to_order_api( $response, $order, $request ) {
	if ( false === class_exists( 'AW_Referrals_Addon' ) ) {
		return $response;
	}

	$data = $response->get_data();
	$advocate = AutomateWoo\Referrals\Advocate_Factory::get( $order->get_user_id() );

	if ( $advocate && AW_Referrals()->options()->type === 'coupon' ) {
		$data['automatewoo_referral_coupon'] = $advocate->get_shareable_coupon();
	}

	$response->set_data( $data );

	return $response;
}

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