Get transaction_id with woocommerce order through REST API
The WordPress woocommerce api response order hook.
/*add this code to your function.php file
now your api will include transaction_id
*/
add_action( 'woocommerce_api_order_response', 'my_woocommerce_api_order', 10, 2);
function my_woocommerce_api_order( $data ) {
//you can do anything with the $data here lets add the transaction id
$data['transaction_id'] = get_post_meta( $data['id'], '_transaction_id', true );
return $data;
}