Skip to main content

State Management

ViewModel Registry​

All ViewModels registered in service_locator.dart:

Future<void> setupServiceLocator() async {
  // Auth
  getIt.registerFactory<AuthViewModel>(() => AuthViewModel(getIt<AuthService>()));

  // Core
  getIt.registerFactory<HomeViewModel>(() => HomeViewModel());
  getIt.registerFactory<AttendanceViewModel>(() => AttendanceViewModel(getIt<AttendanceService>()));
  getIt.registerFactory<ExamViewModel>(() => ExamViewModel(getIt<ExamService>()));
  getIt.registerFactory<ResultViewModel>(() => ResultViewModel(getIt<ResultService>()));
  getIt.registerFactory<AssignmentViewModel>(() => AssignmentViewModel(getIt<AssignmentService>()));
  getIt.registerFactory<LeaveViewModel>(() => LeaveViewModel(getIt<LeaveService>()));
  getIt.registerFactory<EventViewModel>(() => EventViewModel(getIt<EventService>()));
  getIt.registerFactory<AnnouncementViewModel>(() => AnnouncementViewModel(getIt<AnnouncementService>()));
  getIt.registerFactory<SubjectViewModel>(() => SubjectViewModel(getIt<SubjectService>()));
  getIt.registerFactory<TimetableViewModel>(() => TimetableViewModel(getIt<TimetableService>()));
  getIt.registerFactory<StudentViewModel>(() => StudentViewModel(getIt<StudentService>()));
  getIt.registerFactory<CompetitionViewModel>(() => CompetitionViewModel(getIt<CompetitionService>()));
  getIt.registerFactory<MessageViewModel>(() => MessageViewModel(getIt<MessageService>()));
  getIt.registerFactory<NotificationViewModel>(() => NotificationViewModel(getIt<NotificationService>()));
}

Using ViewModels in Screens​

class AttendanceScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer<AttendanceViewModel>(
      builder: (context, vm, _) {
        if (vm.isLoading) return const CircularProgressIndicator();
        if (vm.hasError) return ErrorView(message: vm.errorMessage!);

        // Check evaluation mode before showing write UI
        final authVM = context.watch<AuthViewModel>();
        final canWrite = authVM.canWrite('attendance');

        return Column(
          children: [
            if (!canWrite)
              Container(
                color: Colors.orange.shade100,
                padding: const EdgeInsets.all(8),
                child: const Text('Read-only — Evaluation Mode is active'),
              ),
            Expanded(child: AttendanceList(records: vm.records)),
            if (canWrite) MarkAttendanceFAB(onPressed: vm.markAttendance),
          ],
        );
      },
    );
  }
}

Evaluation Mode Guard in ViewModels​

class AttendanceViewModel extends BaseProvider {
  Future<void> markAttendance(String studentId, String status) async {
    if (isEvaluationMode) {
      setError('Attendance cannot be marked during evaluation period');
      return;
    }
    await requestHandler(() async {
      await _service.updateAttendance(studentId, status);
    });
    notifyListeners();
  }

  bool get isEvaluationMode => _authService.isEvaluationMode;
}