Shipping discount in WooCommerce based on cart subtotal

Question

I want to activate a shipping cost discount based on the cart subtotal.

Examples:

• Order subtotal above R$ 350 -> get 50% of Shipping Discount
• Order subtotal above R$ 450 -> get 70% of Shipping Discount

Therefore, I use the following code:

add_filter( 'woocommerce_package_rates', 'fa_woocommerce_package_rates', 10, 2 );
function fa_woocommerce_package_rates( $rates, $package ) {

    foreach ( $rates as $key => $rate ) {
        $cost = $rate->get_cost();

        // todos os métodos
        $rate->set_cost( $cost * 0.5 ); // 0.5 = 50%

        $rates[ $key ] = $rate;
    }

    return $rates;
}

It works, but i'm struggling to make these rules. Any help would be apreciated.

Answer 1

To determine the shipping discount based on the subtotal you can use the 2nd argument passed to the filter hook, namely: $package. Then you use: $package['cart_subtotal']

So you get:

function filter_woocommerce_package_rates( $rates, $package ) {
    // Get subtotal
    $subtotal = $package['cart_subtotal'];
    
    // Greater than
    if ( $subtotal > 350 ) {
        // 50% discount
        $percentage = 50;

        // If more, adjust percentage
        if ( $subtotal > 450 ) {
            // 70% discount
            $percentage = 70;
        }

        // Loop trough
        foreach ( $rates as $rate_id => $rate ) {
            // Get rate cost
            $cost = $rate->get_cost();

            // New rate cost
            $rate->set_cost( $cost - ( $cost * $percentage ) / 100 );
        }
    }   
    
    return $rates;
}
add_filter( 'woocommerce_package_rates', 'filter_woocommerce_package_rates', 10, 2 );

---

To target certain shipping methods, change:

// Loop trough
foreach ( $rates as $rate_id => $rate ) {
    // Get rate cost
    $cost = $rate->get_cost();

    // New rate cost
    $rate->set_cost( $cost - ( $cost * $percentage ) / 100 );
}

To:

// Loop trough
foreach ( $rates as $rate_id => $rate ) {
    // Get rate cost
    $cost = $rate->get_cost();

    // Targeting shipping method, several can be added, separated by a comma
    if ( array_intersect( array( $rate->method_id, $rate_id ), array( 'flat_rate', 'flat_rate:3' ) ) ) {
        // New rate cost
        $rate->set_cost( $cost - ( $cost * $percentage ) / 100 );
    }
}

---

Hint: for debugging purposes you can temporarily use the second part from this answer