public JsonResult Purchase(int?drink_id)
        {
            if (drink_id == null || drink_id < 1)
            {
                return(Json(new { success = false, message = "Неправильный код напитка", cash = Settings.AppSettings.Cash }, JsonRequestBehavior.AllowGet));
            }

            Core.Drink drink = Core.Drink.GetEntityById(drink_id.Value);
            if (drink.price > Settings.AppSettings.Cash)
            {
                return(Json(new { success = false, message = "Недостаточно средств", cash = Settings.AppSettings.Cash }, JsonRequestBehavior.AllowGet));
            }
            // Спишем средства со счета
            Settings.AppSettings.Cash -= drink.price;
            // Запишем продажу в БД
            Core.Sold sold = new Sold();
            sold.drink_id = drink_id.Value;
            sold.dt       = DateTime.Now;
            sold.Save();
            // Уменьшим количество товара в хранилище
            Core.Store store = Core.Store.GetEntityById(drink_id.Value);
            store.qty--;
            store.Save();

            return(Json(new { success = true, message = "success", cash = Settings.AppSettings.Cash }, JsonRequestBehavior.AllowGet));
        }