Add a fee for a specific product category in Woocommerce

Question

I already found this code here and it works for like 80/90% for me (see below).

This code adds 60 euro to my cart when there is a product from category ID 349 in the

Answer 1

The code you are using is a bit outdated and you should use has_term() Wordpress conditional function to target a product category this way:

add_action( 'woocommerce_cart_calculate_fees','custom_pcat_fee', 20, 1 );
function custom_pcat_fee( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    // Set HERE your categories (can be term IDs, slugs or names) in a coma separated array
    $categories = array('349');
    $fee_amount = 0;

    // Loop through cart items
    foreach( $cart->get_cart() as $cart_item ){
        if( has_term( $categories, 'product_cat', $cart_item['product_id']) )
            $fee_amount = 60;
    }

    // Adding the fee
    if ( $fee_amount > 0 ){
        // Last argument is related to enable tax (true or false)
        WC()->cart->add_fee( __( "Extra bezorgkosten kunstgras", "woocommerce" ), $fee_amount, false );
    }
}

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

A fee of 60 will always be added if there is in cart an item from 349 product category ID.