Add fee for certain products in WooCommerce cart

Question

I have a working script that adds a fee for certain products in an array. But it only adds the fee for the first product in the array.

I have tried different options with my knowledge but it doesn't work. Any advice on what i'm doing wrong?

This is the code:

/* Add fee to specific product*/ 
add_action('woocommerce_cart_calculate_fees', 'statie_geld'); 
function statie_geld() { 
   if (is_admin() && !defined('DOING_AJAX')) {return;} 
   foreach( WC()->cart->get_cart() as $item_keys => $item ) {
     $quantiy = $item['quantity']; //get quantity from cart  
     if( in_array( $item['product_id'], statiegeld_ids() )) { 
     WC()->cart->add_fee(__('Statiegeld Petfles 24'), 3.60 * $quantiy ); 
     } 
   } 
} 
function statiegeld_ids() { 
   return array( 4535, 4537, 89694, 89706, 3223, 4742, 14846, 26972, 32925, 32927, 32929, 37475 ); 
} 

Answer 1

Your code contains some mistakes

• No need to use WC()->cart , $cart is passed to the function
• $quantiy is overwritten on each loop
• Same for adding the fee, this is overwritten on each loop

So you get:

function action_woocommerce_cart_calculate_fees( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) return;
    
    // Initialize
    $quantity = 0;
    
    // Loop though each cart item
    foreach ( $cart->get_cart() as $cart_item ) {
        // Compare
        if ( in_array( $cart_item['product_id'], statiegeld_ids() ) ) {
            // Addition
            // Get product quantity in cart  
            $quantity += $cart_item['quantity'];
        }           
    }
    
    // Greater than
    if ( $quantity > 0 ) {
        // Add fee
        $cart->add_fee( __( 'Statiegeld Petfles 24', 'woocommerce' ), 3.60 * $quantity );
    }
}
add_action( 'woocommerce_cart_calculate_fees', 'action_woocommerce_cart_calculate_fees', 10, 1 );

// Specify the product IDs
function statiegeld_ids() { 
   return array( 4535, 4537, 89694, 89706, 3223, 4742, 14846, 26972, 32925, 32927, 32929, 37475 ); 
}