Add to cart maximun quantity per product with validation in WooCommerce

Question

I want to restrict add to cart button with a max quantity of 10 per product. I want customers cannot purchase more than 10 quantity per product per order.

Here is the code

add_filter( 'woocommerce_add_to_cart_validation', 'restrict_per_product_quantity' );
function restrict_per_product_quantity($cart_item_data) {
    global $woocommerce;
    $item_count = $woocommerce->cart->cart_contents_count;
    if($item_count > 10) {
        wc_add_notice( 'Sorry, Only 10 quantity per product per order is allowed. If you would like to order more please contact support.', 'error' );
        return false;
    }
    return $cart_item_data;
}

---

The issue is this code did not work with per product, it checks the cart, and if there are 10 items in the cart it displays the error.

Answer 1

• woocommerce_add_to_cart_validation contains 5 parameters that you can use
• explanation via comments added in the code

function filter_woocommerce_add_to_cart_validation( $passed, $product_id, $quantity, $variation_id = null, $variations = null ) {
    // Set max allowed
    $max_allowed = 10;
    
    // Error message
    $message = 'max ' . $max_allowed . ' products allowed';
    
    // quantity > max allowed || elseif = when cart not empty
    if ( $quantity > $max_allowed ) {
        wc_add_notice( __( $message, 'woocommerce' ), 'error' );
        $passed = false;   
    } elseif ( ! WC()->cart->is_empty() ) {
        // Get current product id
        $product_id = $variation_id > 0 ? $variation_id : $product_id;
    
        // Cart id
        $product_cart_id = WC()->cart->generate_cart_id( $product_id );
    
        // Find product in cart
        $in_cart = WC()->cart->find_product_in_cart( $product_cart_id );
        
        // True
        if ( $in_cart ) {
            // Get cart
            $cart = WC()->cart->get_cart();

            // Current quantity in cart
            $quantity_in_cart = $cart[$product_cart_id]['quantity'];
            
            // Condition: quanitity in cart + new add quantity greater than max allowed
            if ( $quantity_in_cart + $quantity > $max_allowed ) {           
                wc_add_notice( __( $message, 'woocommerce' ), 'error' );
                $passed = false;
            }
        }
    }
    
    return $passed;
}
add_filter( 'woocommerce_add_to_cart_validation', 'filter_woocommerce_add_to_cart_validation', 10, 5 );