public void AddToCart(Pie pie, int amount)
        {
            var shoppingCartItem =
                _appDbContext.ShoppingCartItems.SingleOrDefault(
                    s => s.Pie.PieId == pie.PieId && s.ShoppingCartId == ShoppingCartId);

            if (shoppingCartItem == null)
            {
                shoppingCartItem = new ShoppingCartItem
                {
                    ShoppingCartId = ShoppingCartId,
                    Pie            = pie,
                    Amount         = 1
                };

                _appDbContext.ShoppingCartItems.Add(shoppingCartItem);
            }
            else
            {
                shoppingCartItem.Amount++;
            }
            _appDbContext.SaveChanges();
        }
        public int RemoveFromCart(Pie pie)
        {
            var shoppingCartItem =
                _appDbContext.ShoppingCartItems.SingleOrDefault(
                    s => s.Pie.PieId == pie.PieId && s.ShoppingCartId == ShoppingCartId);

            var localAmount = 0;

            if (shoppingCartItem != null)
            {
                if (shoppingCartItem.Amount > 1)
                {
                    shoppingCartItem.Amount--;
                    localAmount = shoppingCartItem.Amount;
                }
                else
                {
                    _appDbContext.ShoppingCartItems.Remove(shoppingCartItem);
                }
            }

            _appDbContext.SaveChanges();
            return(localAmount);
        }