public CheckoutViewModel GetCart(string cartId) { var cartItems = checkoutRepository.GetCart(cartId); //sums up the total cost var sum = cartItems.Select(c => c.Price * c.Quantity).Sum(); //put all of the items and the total cost into a new view model var checkoutItems = new CheckoutViewModel(); checkoutItems.Cart = cartItems; checkoutItems.Sum = sum; return(checkoutItems); }