WooCommerce reset quantity before adding to cart (to prevent addition)

Question

When I add a product quantity of 3 to the cart, it's all good.

But after adding 5 more quantities to the cart, I want to quantity in the cart to be 5 and not 8.

I want the last quantity sent to override the quantity before, not add to it.

Also, I want this to behave like this only on a specific product ID.

Which hook is suitable for this?

Answer 1

You could use the woocommerce_add_to_cart hook

In this example, product id 30 is used

function action_woocommerce_add_to_cart ( $cart_item_key, $product_id, $quantity, $variation_id, $variation, $cart_item_data ) {
    // Get current product id
    $product_id = $variation_id > 0 ? $variation_id : $product_id;

    // Specific product ID, compare
    if ( $product_id == 30 ) {
        // Set quantity
        WC()->cart->set_quantity( $cart_item_key, $quantity );      
    }
}
add_action( 'woocommerce_add_to_cart', 'action_woocommerce_add_to_cart', 10, 6 );