public async Task <ActionResult> Maintain(int?id)
        {
            if (id == null)
            {
                return(new HttpStatusCodeResult(HttpStatusCode.BadRequest));
            }
            Room room = await db.Rooms.FindAsync(id);

            if (room == null)
            {
                return(HttpNotFound());
            }

            // 只有处于"活动"状态的会议室才能被"维护"
            if (room.RoomStatus != RoomStatusType.Active)
            {
                return(RedirectToAction("Index"));
            }

            MeetingsInRoomViewModel model = new MeetingsInRoomViewModel();

            model.MeetingRoom = room;
            // 查询该会议室所有已预定但尚未进行的会议,并且提示用户
            model.Meetings = await
                             db.Meetings.Include("Reservationist").Where(m => m.RoomID == id.Value &&
                                                                         m.StartTime >= DateTime.Now).ToListAsync();

            return(View(model));
        }
        public async Task <ActionResult> Delete(int?id)
        {
            if (id == null)
            {
                return(new HttpStatusCodeResult(HttpStatusCode.BadRequest));
            }
            Room room = await db.Rooms.FindAsync(id);

            if (room == null)
            {
                return(HttpNotFound());
            }

            MeetingsInRoomViewModel model = new MeetingsInRoomViewModel();

            model.MeetingRoom = room;
            // 查询该会议室所有已预定但尚未进行的会议,并且提示用户
            model.Meetings = await
                             db.Meetings.Include("Reservationist").Where(m => m.RoomID == id.Value &&
                                                                         m.StartTime >= DateTime.Now).ToListAsync();

            return(View(model));
        }