public int AddCartItem(CartItem cartItem)
        {
            try
            {
                var dbcartitem = new DbCartItem()
                {
                    product_id = cartItem.ProductId,
                    quanity = cartItem.Quanity
                };

                dbcartitem = _dbEntities.CartItems.Add(dbcartitem);
                _dbEntities.SaveChanges();

                return dbcartitem.cart_id;
            }
            catch (Exception ex)
            {
                throw;
            }
        }
        public void UpdateCartItem(CartItem cartItem)
        {
            var dbcartitem = _dbEntities.CartItems.SingleOrDefault(x => x.cart_id == cartItem.CartId);

            if (dbcartitem == null)
            {
                throw new ObjectNotFoundException(string.Format(" Cart Id of :{0} was not found", cartItem.CartId));
            }

            try
            {
                dbcartitem.product_id = cartItem.ProductId;
                dbcartitem.quanity = cartItem.Quanity;
                dbcartitem.date_modified = DateTime.Now;

                _dbEntities.SaveChanges();

            }
            catch (Exception)
            {

                throw;
            }
        }