Add the Coupon Code names to Woocommerce View Order details and email notifications

Question

I noticed that in the View Order Details and email confirmations, it reflects a discount line, but doesn't state the actual Discount Code used. Furthermore, if the discount code is $0.00 (we sometimes have a $0 code for special tracking purposes), it won't even show the code at all. I spent all day trying to find a solution -- can someone give some guidance on this? Thanks.

I got this working so far to get the actual coupon code:

add_action( 'woocommerce_order_details_after_order_table', 'custom_woocommerce_coupon_line' );
function custom_woocommerce_coupon_line( $order_id ) {
    $order    = wc_get_order( $order_id );

    // An order can have no used coupons or also many used coupons
    $coupons  = $order->get_used_coupons();
    $coupons  = count($coupons) > 0 ? implode(',', $coupons) : '';
    echo $coupons;
 }

But can't figure out how to get it into the 'Discount' line... nor why the Discount line doesn't even appear when it's a $0 item with a $0 code used.

Answer 1

Updated - Handling discounts with a zero value

The following code will after "discount" line in order totals lines, displaying the applied coupons to the order:

add_filter( 'woocommerce_get_order_item_totals', 'add_coupons_codes_line_to_order_totals_lines', 10, 3 );
function add_coupons_codes_line_to_order_totals_lines( $total_rows, $order, $tax_display ) {
    // Exit if there is no coupons applied
    if( sizeof( $order->get_used_coupons() ) == 0 )
        return $total_rows;

    $new_total_rows = []; // Initializing

    foreach($total_rows as $key => $total ){
        $new_total_rows[$key] = $total;

        if( $key == 'discount' ){
            // Get applied coupons
            $applied_coupons = $order->get_used_coupons();
            // Insert applied coupon codes in total lines after discount line
            $new_total_rows['coupon_codes'] = array(
                'label' => __('Applied coupons:', 'woocommerce'),
                'value' => implode( ', ', $applied_coupons ),
            );
        }
    }

    return $new_total_rows;
}

Display on customer order view, with 2 applied coupons:

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Additional code version: Handle applied coupons with a zero discount amount use this instead:

add_filter( 'woocommerce_get_order_item_totals', 'add_coupons_codes_line_to_order_totals_lines', 10, 3 );
function add_coupons_codes_line_to_order_totals_lines( $total_rows, $order, $tax_display ) {
    $has_used_coupons = sizeof( $order->get_used_coupons() ) > 0 ? true : false;

    // Exit if there is no coupons applied
    if( ! $has_used_coupons )
        return $total_rows;

    $new_total_rows  = []; // Initializing
    $applied_coupons = $order->get_used_coupons(); // Get applied coupons

    foreach($total_rows as $key => $total ){
        $new_total_rows[$key] = $total;

        // Adding the discount line for orders with applied coupons and zero discount amount
        if( ! isset($total_rows['discount']) && $key === 'shipping' ) {
            $new_total_rows['discount'] = array(
                'label' => __( 'Discount:', 'woocommerce' ),
                'value'    => wc_price(0),
            );
        }

        // Adding applied coupon codes line
        if( $key === 'discount' || isset($new_total_rows['discount']) ){
            // Get applied coupons
            $applied_coupons = $order->get_used_coupons();
            // Insert applied coupon codes in total lines after discount line
            $new_total_rows['coupon_codes'] = array(
                'label' => __('Applied coupons:', 'woocommerce'),
                'value' => implode( ', ', $applied_coupons ),
            );
        }
    }

    return $new_total_rows;
}

Display on email notifications with a coupon that has 0 discount:

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Code goes in function.php file of your active child theme (or active theme). Tested and works.