Video 4:46

     Now we’ll finish the shopping cart, including another gateway component that adds up the amounts in all the Order Items. That requires dragging in the square component that holds the collection of Order Item records.

     We also have to allocate the columns of the multi-column list box to the fields of the Order Item record that we want to display: item name, unit price, quantity, and extended price.

     Notice that the input object to the gateway component offers two functions, total the prices and total the quantities. I’ll switch between them and you will see the behavior change in the application immediately.