WooCommerce check cart items quantity for multiples of 6 starting at 12

Question

I have a client who wishes to sell products (champagne) with the possibility of mixing, in multiples of 6 bottles from 12 bottles. I work under wordpress and woocommerce.

I managed to find a php code which allows to make multiples but I would like it to work only from 12 products (and not from 1 product).

Do you know how to modify this code to make it happen? I am too new to php to find the solution. The plugins that exist are not suitable because of the mix.

Thanks for your help.

Example : I buy 10 bottles of CHAMPAGNE1 + 5 Bottles of CHAMPAGNE2 = 15 items -> an error message say I need multiple of 6 items.

BUT if I buy 1 bottle of CHAMPAGNE1 + 1 bottle of CHAMPAGNE 2 = 2 items -> I can pay, no error message. No need multiple of 6

This is the code I found and tweaked:

add_action( "woocommerce_check_cart_items", "woocommerce_check_cart_quantities" );
function woocommerce_check_cart_quantities() {
    $multiples = 6;
    $total_products > 0;
    foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {
        $total_products += $values["quantity"];
    }
    if ( ( $total_products % $multiples ) > 0 )
        wc_add_notice( sprintf( __("Les commandes se font par lot de %s bouteilles. Merci de vérifier         votre panier. ", "woocommerce"), $multiples ), "error" );
}

Answer 1

Updated

There is a little mistake and something is missing in your code. Try the following instead:

add_action( "woocommerce_check_cart_items", "woocommerce_check_cart_quantities" );
function woocommerce_check_cart_quantities() {
    $multiples      = 6;
    $total_quantity = 0;
    $qty_threshold  = 12;

    foreach ( WC()->cart->get_cart() as => $item ) {
        $total_quantity += $item["quantity"];
    }

    if ( $total_quantity > $qty_threshold && ( $total_quantity % $multiples ) > 0 ) {
        wc_add_notice( sprintf( __("Orders are made in batches of %s bottles. Please check your cart. ", "woocommerce"), $multiples ), "error" );
    }
}