WooCommerce minimum quantity per category across multiple products

Question

In WooCommerce, I aim to enforce a minimum quantity restriction on purchased items by category.

Here's an example:

• For products 1, 2, and 3 (all in the Shoes category), the combined minimum quantity is 10.
• For products 4, 5, and 6 (all in the Pants category), the combined minimum quantity is 10.
• For products 7, 8, and 9 (all in the Shirt category), the combined minimum quantity is 10.

Each category should have at least 10 products ordered. However, these can be spread across multiple products within the same category.

I found a piece of code that partially meets my needs. It displays the minimum notice, but it allows mixing of multiple categories, which is not what I want. Here's the code:

add_action('woocommerce_check_cart_items', 'custom_set_min_total');
function custom_set_min_total()
{
    if (is_cart() || is_checkout()) {

        global $woocommerce, $product;
        $i = 0;

        foreach ($woocommerce->cart->cart_contents as $product) :
            $minimum_cart_product_total = 10;

            if (has_term( array('oneya', 'twoya'), 'product_cat', $product['product_id'])) :
                $total_quantity += $product['quantity'];
            endif;

        endforeach;

        foreach ($woocommerce->cart->cart_contents as $product) :
            if (has_term( array('oneya', 'twoya'), 'product_cat', $product['product_id'])) :
                if ($total_quantity < $minimum_cart_product_total && $i == 0) {
                    wc_add_notice(
                        sprintf(
                            'A minimum of 10 products is required per unique design. You have not met these requirements. Please add at least 10 items to proceed with your order.',
                            $minimum_cart_product_total,
                            $total_quantity
                        ),
                        'error'
                    );
                }
                $i++;
            endif;
        endforeach;
    }
}

Answer 1

To restrict items to a minimum combined quantity (10) per category, try the following:

add_action('woocommerce_check_cart_items', 'minimum_item_quantity_by_category');
function minimum_item_quantity_by_category(){
    // Your categories settings (count initialized to zero for each)
    $terms_count = ['Shoes' => 0, 'Pants' => 0, 'Shirt' => 0 ];
    
    // Loop through cart items
    foreach ( WC()->cart->get_cart() as $item ) {
        // Loop through categories
        foreach ( array_keys($terms_count) as $category ) {
            if ( has_term( $category, 'product_cat', $item['product_id']) ) {
                $terms_count[$category] += $item['quantity'];
            } 
        }
    }

    // Loop through category / count array
    foreach ( $terms_count as $category => $count ) {
        if ( $count != 0 && $count < 10 ) {
            $term = get_term_by('name', $category, 'product_cat');
            wc_add_notice( sprintf( 
                __('A Minimum of 10 items from %s category is required. Add %d more to proceed with your order.', 'woocommerce'),
            '<a href="'.get_term_link($term).'">'.$category.'</a>', (10 - $count) ), 'error' );
        }
    }
}

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