php - Set item quantity to multiples of “x” for products in a specific category in Woocommerce

Question

I found online a snippet that allows you to set in the cart a minimum purchase to multiple quantities of “6”.

Here it is:

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( __('You need to buy in quantities of %s products', 'woocommerce'), $multiples ), 'error' );
}

I want this rule to be valid only for products belonging to a specific category, with “id = 35”.

All products in other categories can also be purchased in smaller quantities.

Answer 1

Update (extended to parent product categories too)

Try the following that will make your code work only for a specific product category:

// Custom conditional function that checks also for parent product categories
function has_product_category( $product_id, $category_ids ) {
    $term_ids = array(); // Initializing

    // Loop through the current product category terms to get only parent main category term
    foreach( get_the_terms( $product_id, 'product_cat' ) as $term ){
        if( $term->parent > 0 ){
            $term_ids[] = $term->parent; // Set the parent product category
            $term_ids[] = $term->term_id;
        } else {
            $term_ids[] = $term->term_id;
        }
    }
    return array_intersect( $category_ids, array_unique($term_ids) );
}


add_action( 'woocommerce_check_cart_items', 'woocommerce_check_cart_quantities' );
function woocommerce_check_cart_quantities() {
    $multiples = 6;
    $total_products = 0;
    $category_ids = array( 35 );
    $found = false;

    foreach ( WC()->cart->get_cart() as $cart_item ) {
        if ( has_product_category( $cart_item['product_id'], $category_ids ) ) {
            $total_products += $cart_item['quantity'];
            $found = true;
        }
    }
    if ( ( $total_products % $multiples ) > 0 && $found )
        wc_add_notice( sprintf( __('You need to buy in quantities of %s products', 'woocommerce'), $multiples ), 'error' );
}

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