flutter_bloc event is not trigger after Migrate to flutter_bloc v 8.0.0 from v7.2.1

user_1559116 0
Viewed 963

I tried to migrate flutter_bloc v 8.0.0. After I read the documentation, then I know that I need to migrate mapEventToState to on. After that I don't get an error but _getMonks event is not trigger. Here is my code. Is there anything I miss out?

class MonkBloc extends Bloc<MonkEvent, MonkState> {
   final MonkRespository monkRespository;
   late List<Monk> monks;

   MonkBloc({required this.monkRespository}) : super(MonkInitial()) {
       on<GetMonksEvent>((event, emit) => _getMonks);
       on<MonkSearchEvent>((event, emit) => _searchMonks);
   }

   Stream<MonkState> _getMonks(Emitter<MonkState> emit) async* {
     emit(MonkLoading());
     try {
        final List<Monk> monks = await monkRespository.fetchMonks();
        emit(MonkLoaded(monks: monks));
     } catch (e) {
     emit (MonkError(error: (e.toString())));
     }
  }

  Stream<MonkState> _searchMonks(String query, Emitter<MonkState> emit) async* {
emit(MonkLoading());
try {
  final List<Monk> monks = await monkRespository.searchMonks(query);
  emit(MonkLoaded(monks: monks));
} catch (e) {
  emit(MonkError(error: (e.toString())));
}
}
}

class MonkScreen extends StatefulWidget {
  static const routeName = '/monk';
  final String? title;
  final MonkScreenMode? screenMode;
  const MonkScreen({Key? key, this.title, this.screenMode}) : super(key: key);

  @override
  State<MonkScreen> createState() => _MonkScreenState();
  }

  class _MonkScreenState extends State<MonkScreen> {

  _loadMonks() async {

    BlocProvider.of<MonkBloc>(context).add(const GetMonksEvent()); 
  }   

  @override
  void initState() {
    super.initState();
    _loadMonks();
  }

  @override
  Widget build(BuildContext context) {
  return BaseWidget(
  child: Scaffold(
    backgroundColor: Theme.of(context).backgroundColor,
    appBar: AppBar(
      centerTitle: true,
      backgroundColor: Theme.of(context).backgroundColor,
      elevation: 0,
      title: AutoSizeText(
        widget.title!,
        style: Theme.of(context).appBarTheme.titleTextStyle,
      ),
      leading: IconButton(
        onPressed: () {
          Navigator.pop(context);
        },
        icon: Icon(
          Icons.arrow_back,
          color: Theme.of(context).primaryIconTheme.color!,
        ),
      ),
      actions: [
        IconButton(
          onPressed: () {
            showSearch(
                context: context,
                delegate: MonkSearch(screenMode: widget.screenMode!));
          },
          icon: Icon(
            Icons.search,
            color: Theme.of(context).primaryIconTheme.color!,
          ),
        ),
      ],
    ),
    body: BlocBuilder<MonkBloc, MonkState>(
      builder: (BuildContext context, MonkState monkState) {
        if (monkState is MonkError) {
          return const SomethingWentWrongScreen();
        } else if (monkState is MonkLoaded) {
          return listViewBuilder(
              context, monkState.monks, widget.screenMode!);
        }
        return const Center(
          child: CircularProgressIndicator(),
        );
      },
    ),
  ),
);
}
}
flutter-bloc bloc dart flutter
3 Answers

This is how I migrate the code. In case someone needed it.

class MonkBloc extends Bloc<MonkEvent, MonkState> {
final MonkRespository monkRespository;
late List<Monk> monks;

MonkBloc({required this.monkRespository}) : super(MonkInitial()) {
on<GetMonksEvent>((event, emit) async {
await _getMonks(emit);
});
on<MonkSearchEvent>((event, emit) async {
await _searchMonks(event.query, emit);
});
}

 Future<void> _getMonks(Emitter<MonkState> emit) async {
 emit(MonkLoading());
 try {
 final List<Monk> monks = await monkRespository.fetchMonks();
  emit(MonkLoaded(monks: monks));
 } catch (e) {
 emit (MonkError(error: (e.toString())));
 }
 }

 Future<void> _searchMonks(String query, Emitter<MonkState> emit) async 
 {
 emit(MonkLoading());
  try {
  final List<Monk> monks = await monkRespository.searchMonks(query);
 emit(MonkLoaded(monks: monks));
 } catch (e) {
 emit(MonkError(error: (e.toString())));
 }
 }
 }
user_15591160 
class APIBloc extends Bloc<APIEvents, APIState> {
  //
  final APIRepo apiRepo;

  APIBloc({required this.apiRepo}) : super(APIInitState()) {
    on<APIEvents>(_addToValue);
  }

  Future<void> _addToValue(APIEvents event, Emitter<APIState> emit) async {
    print("onEvent");
    emit(APILoading());
    emit.forEach(
        Stream.fromFuture(_callAPI(event).catchError((onError) {
          return onError;
        })), onData: (value) {
      if (value is Response)
        return APILoaded(response: value as Response);
      else {
        return value as APIListError;
      }
    });
  }

  Future<Object> _callAPI(APIEvents event) async {
    try {
      if (event is FetchDashBoard) {
        return await apiRepo.getDashboardData(event.requestParams);
      } else if (event is DoLogin) {
        return await apiRepo.doLogin(event.requestParams);
      } else {
        throw (APIListError(
          error: NoInternetException('No Internet'),
        ));
      }
    } on SocketException {
      throw (APIListError(
        error: NoInternetException('No Internet'),
      ));
    } on HttpException {
      throw (APIListError(
        error: NoServiceFoundException('No Service Found'),
      ));
    } on FormatException {
      throw (APIListError(
        error: InvalidFormatException('Invalid Response format'),
      ));
    } catch (e) {
      throw (APIListError(
        error: UnknownException('Unknown Error'),
      ));
    }
  }
}

follow below site if need more clarify code. https://flutterlearneasyway.blogspot.com/2021/11/flutter-bloc-pattern-800-call-api.html

user_32220050

There is a typo here.

on<GetMonksEvent>((event, emit) => _getMonks);

You must call _getMonks with args or just pass the event listener itself:

Use this one

on<GetMonksEvent>((event, emit) => _getMonks(event, emit));

or the better one

on<GetMonksEvent>(_getMonks);
user_83466050
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