Flutter, Bloc how to process SocketException and check network speed

Issue

In my application I have some free data that the user loads when they open it for the first time. I have screen where I need to load some other data from the server, that can be purchased, and I want to process if internet connection is available and also if user loading data from network for over 5 seconds, emit to them the next state and display data that user already loaded.

This is what I have right now, if user doesn't have internet connection, CheckListTemplateError emits to them, but I want to emit CheckListTemplateLoaded with data from loadedPaidTemplates

in code comment I will explain which part of code loading from server

How I can process if internet connection is available and if user loading data from server for over 5 seconds, emit to them the state with local loaded data?

  Future<void> _loadCheckListTemplates(OnCheckListTemplateLoad event, Emitter emit) async {
    emit(CheckListTemplateLoading());
    try {
      // this is what I load from local data
      final List<CheckListTemplate> loadedTemplates = await _checkListRepository.getLocalCheckListTempaltes();
      // this is loading from server
      final List<CheckListTemplate> loadedPaidTemplates = await _checkListRepository.getPaidCheckListTempaltes();
      for (int i = 0; i < loadedPaidTemplates.length; i++) {
        loadedTemplates.add(loadedPaidTemplates[i]);
      }
      final List<String> loadedPaidCheckListIds = await _checkListRepository.getPaidCheckListTemplateData();
      emit(CheckListTemplateLoaded(loadedTemplates: loadedTemplates, paidCheckListsIds: loadedPaidCheckListIds));
    } catch (e) {
      emit(CheckListTemplateError());
    }
  }

Solution

I found code for checking internet connection, but I'm not sure if it's 100% correct, so you should take it with caution, but you can try something like this:

Future<void> _loadCheckListTemplates( OnCheckListTemplateLoad event, Emitter emit) async {
    emit(CheckListTemplateLoading());
    try {
      // this is what i load from local data
      final List<CheckListTemplate> loadedTemplates =
          await _checkListRepository.getLocalCheckListTempaltes();
      bool _isConnectionSuccessful = false;
      // check for internet connection
      final response = await InternetAddress.lookup('www.google.com');
      _isConnectionSuccessful = response.isNotEmpty;

      if (!_isConnectionSuccessful) {
        // do something if there is no internet connection or in your catch block
      }
      // initializing your 5 second timer before your next request
      final timer = Timer(Duration(seconds: 5), () {
        // do something if your request takes more then 5 seconds
      });
      // this is loading from server
      final List<CheckListTemplate> loadedPaidTemplates =
          await _checkListRepository.getPaidCheckListTempaltes();
      //stop the timer if previous request finished in less then 5 seconds
      if (timer.isActive) timer.cancel();

      for (int i = 0; i < loadedPaidTemplates.length; i++) {
        loadedTemplates.add(loadedPaidTemplates[i]);
      }
      final List<String> loadedPaidCheckListIds =
          await _checkListRepository.getPaidCheckListTemplateData();
      emit(CheckListTemplateLoaded(
          loadedTemplates: loadedTemplates,
          paidCheckListsIds: loadedPaidCheckListIds));
    } catch (e) {
      emit(CheckListTemplateError());
    }
  }

Answered By - Ante Bule