Custom Coupon type woocommerce wordpress

In newer versions of WooCommerce, you will need to

1. Register a custom coupon type
2. Validate the coupon
3. Calculate & Apply the discount

Register custom coupon type

add_filter( 'woocommerce_coupon_discount_types', 'custom_coupon_type',10, 1);
function custom_coupon_type( $discount_types ) {        
    $discount_types['my_type'] =__( 'My New Coupon Type', 'woocommerce' );  
    return $discount_types;
}

Validate the coupon

add_filter('woocommerce_coupon_is_valid_for_product', 'validate_custom_coupon', 10, 4);
function validate_custom_coupon($valid, $product, $coupon, $values){
    if ( ! $coupon->is_type( array( 'my_type' ) ) ) {
        return $valid;
    }

    $product_cats = wp_get_post_terms( $product->id, 'product_cat', array( "fields" => "ids" ) );
    
    // SPECIFIC PRODUCTS ARE DISCOUNTED
    if ( sizeof( $coupon->product_ids ) > 0 ) {
        if ( in_array( $product->id, $coupon->product_ids ) || ( isset( $product->variation_id ) && in_array( $product->variation_id, $coupon->product_ids ) ) || in_array( $product->get_parent(), $coupon->product_ids ) ) {
            $valid = true;
        }
    }

    // CATEGORY DISCOUNTS
    if ( sizeof( $coupon->product_categories ) > 0 ) {
        if ( sizeof( array_intersect( $product_cats, $coupon->product_categories ) ) > 0 ) {
            $valid = true;
        }
    }

    // IF ALL ITEMS ARE DISCOUNTED
    if ( ! sizeof( $coupon->product_ids ) && ! sizeof( $coupon->product_categories ) ) {            
        $valid = true;
    }
    
    // SPECIFIC PRODUCT IDs EXLCUDED FROM DISCOUNT
    if ( sizeof( $coupon->exclude_product_ids ) > 0 ) {
        if ( in_array( $product->id, $coupon->exclude_product_ids ) || ( isset( $product->variation_id ) && in_array( $product->variation_id, $coupon->exclude_product_ids ) ) || in_array( $product->get_parent(), $coupon->exclude_product_ids ) ) {
            $valid = false;
        }
    }
    
    // SPECIFIC CATEGORIES EXLCUDED FROM THE DISCOUNT
    if ( sizeof( $coupon->exclude_product_categories ) > 0 ) {
        if ( sizeof( array_intersect( $product_cats, $coupon->exclude_product_categories ) ) > 0 ) {
            $valid = false;
        }
    }

    // SALE ITEMS EXCLUDED FROM DISCOUNT
    if ( $coupon->exclude_sale_items == 'yes' ) {
        $product_ids_on_sale = wc_get_product_ids_on_sale();

        if ( isset( $product->variation_id ) ) {
            if ( in_array( $product->variation_id, $product_ids_on_sale, true ) ) {
                $valid = false;
            }
        } elseif ( in_array( $product->id, $product_ids_on_sale, true ) ) {
            $valid = false;
        }
    }

    return $valid;
}

Calculate & Apply Discount

add_filter('woocommerce_coupon_get_discount_amount', 'wc_cpn_disc', 10, 5);
function wc_cpn_disc($discount, $discounting_amount, $cart_item, $single, $coupon) {
    // IF TYPE MATCHES PERFORM CUSTOM CALCULATION
    if ($coupon->type == 'my_type')
        $discount = $cart_item['quantity'] * 2000;        
    
    return $discount;
}

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Sources:

• @raju_odi’s answer on this exact question
• @Chris Morris’s answer to Woocommerce custom coupon type with custom discount always return 0