Exclude add-ons cost in coupon discounts

exclude_addons_cost_in_coupons.php

<?php
/**
 * Exclude add-ons cost in coupon discounts
 * @return discount amount
 */

add_filter( 'woocommerce_coupon_get_discount_amount', function( $amount, $discounting_amount, $cart_item, $single, $coupon ) {
	
	$apply_coupon = array( '1097_1772' ); // GroupId_FieldId
	
	if ( $cart_item['product_extras']['price_with_extras'] > 0 ) {
		if ( $coupon->get_meta('discount_type') == 'percent' ) {
			$percent_discount = $coupon->get_amount() / 100;
			$amount = 0;

			if ( count( $apply_coupon ) ) {
				foreach ( $apply_coupon as $field ) {
					list( $group_id, $field_id ) = explode( '_', $field );
					$amount += $cart_item['product_extras']['groups'][$group_id][$field_id]['price'] * $cart_item['quantity'];
				}
			}
			
			$amount += $cart_item['product_extras']['original_price'] * $cart_item['quantity'];
			$amount *= $percent_discount;
		}
	}

	return $amount;

}, 10, 5 );

The snippet overrides the coupon discount amount so that it exempts the add-ons costs from the computation. Currently, this only applies to percentage discounts.

If you want certain fields to add to the main product price before applying the discount, you can update this line:

$apply_coupon = array( '1097_1772' ); // GroupId_FieldId

Just specify the group ID and field ID as a single item. You can add more fields (comma-separated) like so:

$apply_coupon = array( '1097_1772', '2023_2024' ); // GroupId_FieldId

Otherwise, set the array empty so that the entire add-ons total is not included: $apply_coupon = array( );

An example:

Product price = 100
Field 1 (#1772) = 100
Field 2 (#2024) = 100
Field 3 (#2025) = 100

If you apply a 10% coupon discount, the discount amount will be 30 (Product price + Field 1 + Field 2).