public void UpdateCart(ShoppingCart cart)
 {
     TryUpdateModel(cart);
     if (ModelState.IsValid)
     {
         // Do something
     }
 }
        public ShoppingCart SelectModel()
        {
            var cart = new ShoppingCart()
            {
                Title = "Test Cart",
                Address = new Address {
                    FirstLine = "First Line",
                    SectionLine = "Second Line"
                }
            };

            return cart;
        }