//returns the food items for the user identified by uid, that have been purchased between leftTime and rightTime
        //this function is not used anymore but i have not delete it just in case I will need it again
        public List <BFoodItem> getFoodList(long uid, DateTime leftTime, DateTime rightTime)
        {
            FoodItemAccess   fia        = new FoodItemAccess();
            List <FoodItem>  food_list  = fia.getFoodList(uid, leftTime, rightTime);
            List <BFoodItem> bfood_list = new List <BFoodItem>();

            foreach (FoodItem fi in food_list)
            {
                bfood_list.Add(convert_to_bfi(fi));
            }
            return(bfood_list);
        }