title: Get product id on checkout process in WooCommerce
body: <p>At checkout I need to block delivery in certain cities for a specific product (not all products). When user fills in a city that should be blocked based on a list that I defined, the checkout process blocks the order and a custom notice error appear perfectly as desired.</p>
  
  <p>I use this code to block delivery in certain city:</p>
  
  <pre><code>add_action( 'woocommerce_checkout_process', 'shipping_validate_city' );
  function shipping_validate_city() {
      if ( in_array( $product_id, array( 3059, 3058) ) ) {
          $disableCityList = array (
              'Rabat',
              'Temara',
              'Sale',
              'Tamessna',
          );
          $billingCity = isset( $_POST['billing_city'] ) ? trim( $_POST['billing_city'] ) : '';
          $billingCity = str_replace(array('-','_'),' ',$billingCity);
          $billingCity = ucwords($billingCity);
  
          if (in_array($billingCity, $disableCityList))
          {
              wc_add_notice( __('this product not allowed shipping for the city you mentioned') , 'error' );
          }
      }
  }
  </code></pre>
  
  <p>My problem is. How can I do this for specific product only?</p>