Changes in the Customer wishes

Change dish quantity

The logic of this method is similar to that of adding order items.

• Retrieve the order and fetch the menu items.
• Another thing is that we assure that each of the menu items is an order item. Because if a menu item is not part of an order, there may be some mistake.
• changeItemsQuantity() model helper is simpler. It updates the quantity of each order item as requested and updates the totals, respectively.