make a coupon that discount based on weight

Question

I have been trying to make a Coupon that makes a discount based on the cart weight when a coupon is used.

I have achieved something using a fixed amount coupon (with fixed value zero) and adding fees :

 $cart_weight = $cart->get_cart_contents_weight() ;

and

$cart->add_fee( 'Discount ' . $coupon_code, $cost* -1 , false );

Even it works ,I dont like this, I would like to have it as a regular coupon. Is there any way? Thanks

Answer 1

Sure, it's possible, you only have to create a unique coupon and apply it to the cart instead of adding a negative fee

//ADD coupon based of cart weight
add_action( 'woocommerce_before_calculate_totals', 'generate_coupon_based_on_total_weight' );
function generate_coupon_based_on_total_weight( $cart ) {
    // Set the threshold weight for applying the coupon
    $threshold_weight = 10;
    $discount_amount = 2;
    $coupon_prefix = 'weight_';

    $total_weight = $cart->get_cart_contents_weight() ;


    // Check if the total weight is greater than or equal to the threshold weight
    if ( $total_weight >= $threshold_weight ) {
        // Check if the coupon code with the "weight_" prefix has already been applied
        if ( has_coupon_code_with_prefix( $coupon_prefix ) ) {
            // Coupon code already applied, do nothing
            return;
        }

        // Generate a unique coupon code
        $coupon_code = uniqid( $coupon_prefix );

        // Create a new coupon object
        $coupon = new WC_Coupon();
        $coupon->set_code( $coupon_code );
        $coupon->set_amount( $discount_amount ); // Set the coupon amount
        $coupon->set_individual_use( true ); // Set the coupon to be used only once
        $coupon->set_usage_limit( 1 ); // Set the usage limit to 1
        $coupon->save(); // Save the coupon

        // Apply the coupon to the cart
        $cart->add_discount( $coupon_code );
    } else {
        // Total weight is less than the threshold, remove the coupon if it exists
        remove_coupon_from_cart( $coupon_prefix );
    }
}

function has_coupon_code_with_prefix( $prefix ) {
    // Get the applied coupons
    $applied_coupons = WC()->cart->get_applied_coupons();

    // Check if there are any applied coupons
    if ( ! empty( $applied_coupons ) ) {
        // Iterate through the applied coupons
        foreach ( $applied_coupons as $coupon_code ) {
            // Check if the coupon code starts with the specified prefix
            if ( strpos( $coupon_code, $prefix ) === 0 ) {
                // There is a coupon code applied that starts with the specified prefix
                return true;
            }
        }
    }

    // No coupon code was found that starts with the specified prefix
    return false;
}


function remove_coupon_from_cart($prefix) {
    global $woocommerce;

    // Get the cart object
    $cart = $woocommerce->cart;

    // Get the coupon codes applied to the cart
    $coupon_codes = $cart->get_coupons();

    // Loop through the coupon codes and remove any that start with the specified prefix
    foreach ($coupon_codes as $code => $coupon) {
        if (strpos($code, $prefix) === 0) {
            $cart->remove_coupon($code);
            // Save the updated cart
            $cart->calculate_totals();
        }
    }
}

The main idea of this function is to apply a discount coupon to the user's cart if the total weight of the products in the cart meets a certain threshold, and to remove the coupon if the total weight falls below the threshold.

The function is triggered by the woocommerce_before_calculate_totals action, which occurs before the total cost of the products in the cart is calculated.

The function first sets a few variables:

• $threshold_weight: This is the weight that the total weight of the products in the cart must meet or exceed in order for the coupon to be applied.
• $discount_amount: This is the amount of the discount that will be applied if the coupon is applied.
• $coupon_prefix: This is a prefix that will be added to the coupon code to make it unique.

The function then calculates the total weight of the products in the cart using the get_cart_contents_weight method.

Next, the function checks if the total weight is greater than or equal to the threshold weight. If it is, the function generates a unique coupon code using the uniqid function and the $coupon_prefix variable, and creates a new coupon object using the WC_Coupon class. The coupon object is then configured with the discount amount, individual use, and usage limit. Finally, the coupon is saved and applied to the cart using the add_discount method.

If the total weight is less than the threshold weight, the function removes the coupon from the cart if it exists by calling the remove_coupon_from_cart function and passing in the $coupon_prefix variable.

Overall, this function allows you to apply a discount coupon to the user's cart if the total weight of the products in the cart meets a certain threshold, and to remove the coupon if the total weight falls below the threshold.