Replace coupon form with URL argument

Listens to cart page URL argument for `coupon_code`.

Consider the Replace coupon form with a pop-up link code snippet in conjunction with this one. Also could be combined with code to remove the coupon form in cart and/or remove the coupon banner in checkout.

If you’re looking for advanced functionality related to this code, check out the official extension WooCommerce URL Coupons.

add_action( 'woocommerce_cart_calculate_fees', function() {

	// Skip Admin Non AJAX
	if( is_admin() && ! defined( 'DOING_AJAX' ) ) {

	// Get Coupon Code From Query
	$coupon_code = isset( $_GET['coupon_code'] )
		? sanitize_text_field( $_GET['coupon_code'] ) : '';

	// Require Coupon Code And Cart Session
	if( ! $coupon_code || empty( WC()->session ) ) {

	// Maybe Boot Cart Session
	if( ! WC()->session->has_session() ) {
		WC()->session->set_customer_session_cookie( true );

	// Apply Coupon Unless Preexists
	if( ! WC()->cart->has_discount( $coupon_code ) ) {
		WC()->cart->add_discount( $coupon_code );

} );

Instructions for Replace coupon form with URL argument

  1. Log into a staging or locally hosted clone of your site.
  2. Install and activate Code Snippets plugin.
  3. WP Admin > Snippets > Add New
  4. Copy and paste the code from the section above.
  5. Check to ensure formatting came over properly.
  6. Customize the code as desired.
  7. Add a meaningful title.
  8. Select whether to run on front-end or back-end (or both).
  9. Click “Save and Activate”.
  10. Test your site to ensure it works.
  11. Disable if any problems, or recover.
  12. Repeat for live environment.

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