如果在 Woocommerce 中应用了特定的优惠券，则更改统一费率运输方式成本

Question

I have a specific coupon which is special50 . When someone applied this coupon on the store then a new shipping method need to add. When current shipping method price is $50 (flat rate) and after applying coupon new shipping method, pricing will be $25. In a word, if you apply this coupon you will receive 50% OFF on products(which WooCommerce has already provided to us) and 50% OFF on shipping(which really I need).

add_action( 'woocommerce_flat_rate_shipping_add_rate', 'add_another_custom_flat_rate', 10, 2 );
    function add_another_custom_flat_rate( $method, $rate ) {
        $new_rate          = $rate;
        $new_rate['id']    .= ':' . 'custom_rate_name';
        $new_rate['label'] = 'Shipping and handling'; 
    global $woocommerce, $wpdb;
        $coupon = "SELECT post_title FROM {$wpdb->posts} WHERE post_title='special50' AND post_type ='shop_coupon' AND post_status ='publish'";
        if(in_array($coupon_id, $woocommerce->cart->applied_coupons)){
            $cost = 25; 
        }
        $new_rate['cost']  = $cost;
        $method->add_rate( $new_rate );
    }

Answer 1

This can be done using the following custom function hooked in woocommerce_package_rates filter hook, without any need of creating an additional discounted flat rate. The following code will change the "flat rate" shipping method cost when 'special50' coupon is applied.

You should first "Enable debug mode" in Woocommerce settings > shipping > Shipping options.

The code:

add_filter('woocommerce_package_rates', 'coupon_discount_on_flat_rate', 10, 2);
function coupon_discount_on_flat_rate( $rates, $package ){
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) 
        return $rates;

    // Checking for 'special50' in applied coupons
    if( in_array( 'special50', WC()->cart->get_applied_coupons() ) ){
        foreach ( $rates as $rate_key => $rate ){
            $has_taxes = false;
            // Targeting "flat rate" shipping method
            if( $rate->method_id === 'flat_rate' ){
                // Set 50% of the cost
                $rates[$rate_key]->cost = $rates[$rate_key]->cost / 2;

                // Taxes rate cost (if enabled)
                foreach ($rates[$rate_key]->taxes as $key => $tax){
                    if( $rates[$rate_key]->taxes[$key] > 0 ){
                        $has_taxes = true;
                        // set 50% of the cost
                        $taxes[$key] = $rates[$rate_key]->taxes[$key] / 2;
                    }
                }
                if( $has_taxes )
                    $rates[$rate_key]->taxes = $taxes;
            }
        }
    }
    return $rates;
}

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

Dont forget to disable "Enable debug mode" once this has been tested and works.