public OrderViewModel(GenericService <Order> orderService, GenericService <Room> roomService, GenericService <Client> clientService, GenericService <Service> serviceService)
 {
     service             = orderService;
     this.roomService    = roomService;
     this.clientService  = clientService;
     this.serviceService = serviceService;
     WorkingItem         = new Order();
     finishOrderCommand  = new DelegateCommand((o) => { if (SelectedItem == null)
                                                        {
                                                            return;
                                                        }
                                                        SelectedItem.FinishOrder(); service.Update(SelectedItem); SelectedItem.Room.State = RoomState.Free; roomService.Update(SelectedItem.Room); NotifyPropertyChanged("Items"); Update(); });
     useServiceCommand = new DelegateCommand((o) => { if (SelectedItem == null || SelectedItem.EndDate == null || Service == null)
                                                      {
                                                          return;
                                                      }
                                                      SelectedItem.UseService(Service); service.Update(SelectedItem);  NotifyPropertyChanged("Items"); });
 }