public BaseViewModel()
 {
     _classesManager  = new ClassesManager();
     _clientsManager  = new ClientsManager();
     _roomsManager    = new RoomsManager();
     _workersManager  = new WorkersManager();
     _workPlanManager = new WorkPlanManager();
 }
        public WorkPlanViewModel()
        {
            AddWorkPlanElementCommand    = new BaseCommand(AddWorkPlanElement);
            EditWorkPlanElementCommand   = new BaseCommand(EditWorkPlanElement);
            DeleteWorkPlanElementCommand = new BaseCommand(DeleteWorkPlanElement);
            SaveCommand          = new BaseCommand(SaveChanges);
            CancelCommand        = new BaseCommand(Cancel);
            ShowTimetableCommand = new BaseCommand(ShowTimeTable);

            _roomsManager    = GetRoomsManager();
            _classesManager  = GetClassesManager();
            _workPlanManager = GetWorkPlanManager();
            _workersManager  = GetWorkersManagerr();

            RefreshWorkPlanElements();
        }