i have two blocs that must listen to each other, how do i pass one as a parameter to the other? - flutter

Question

**Hello I am new to flutter and bloc architecture.
I am trying to build a simple quiz app that has a timer.
On the quiz page, I have two blocs, a counter cubit to navigate to the next question, and a triviabloc for quiz activities like answer selection.
I am using MultiBlovProvider to provide the blocs.
I need each bloc to communicate with each other. Since each of the blocs is a parameter to the other, how do I pass it in the multiblocprovider
?**
var bloc = TriviaBloc();
var con = CountDownController();
// ignore: close_sinks
var cubit = CounterCubit(
bloc: bloc, controller: con);
return MultiBlocProvider(
providers: [
BlocProvider<TriviaBloc>(
create: (context) => bloc,
),
BlocProvider<CounterCubit>(
create: (context) => cubit)
],
child:
QuestionScreen(trivia: questions),
);
the cubit
class CounterCubit extends Cubit<int> {
StreamSubscription sub;
CounterCubit({this.controller, this.bloc}) : super(0) {
sub = bloc.listen((state) {
if (state is AnswerCorrect || state is AnswerNotCorrect) {
controller.pause();
}
});
}
final TriviaBloc bloc;
final CountDownController controller;
void increment() => emit(state + 1);
#override
Future<void> close() {
sub?.cancel();
return super.close();
}
#override
void onChange(Change<int> change) {
print(change);
super.onChange(change);
}
}
the bloc that must listen to the cubit
class TriviaBloc extends Bloc<TriviaEvent, TriviaState> {
StreamSubscription sub;
TriviaBloc({this.cubit}) : super(TriviaInitial()) {
sub = cubit.listen(
(state) async* {
if (state != 0) {
yield TriviaInitial();
}
},
);
}
final CounterCubit cubit;
Stream<TriviaState> mapEventToState(TriviaEvent event) async* {
if (event is AnswerCLicked) {
print(event.answer);
if (event.answer == event.correctAnswer) {
yield AnswerCorrect();
} else {
yield AnswerNotCorrect();
}
}
if (event is NoAnswerChosen) {
yield ShowAnswer();
}
}
#override
Future<void> close() {
sub?.cancel();
return super.close();
}
}
Thank you

Answer 1

You pass one bloc as an argument to a 2nd bloc. Now, within the 2nd bloc, you can get values from the 1st bloc's state. This is an approach for that:
if (userBloc.state is AppSettled) {
achievements = (userBloc.state as AppSettled).achievements;
userBloc is the bloc that I passed to the 2nd bloc, AppSettled is a state of userBloc, and achievements is a variable defined within that state.
In order to pass data back, you can this answer

Answer 2

Not sure if this is what you are looking for, but this is what I do to make sure that if the user authorization state changes they JobListCubit actually triggers a route to authorization screen.
In my main.dart:
MultiBlocProvider(
providers: [
BlocProvider<UserAuthCubit>(
lazy: true,
create: (context) => UserAuthCubit(
UserAuthRepository(),
),
),
BlocProvider<JobListCubit>(
lazy: true,
create: (context) => JobListCubit(
jobListRepository: JobListRepository(),
userAuthCubit: BlocProvider.of<UserAuthCubit>(context),
)),
....
Then in my JobListCubit:
class JobListCubit extends Cubit<JobListState>
with HydratedMixin<JobListState> {
JobListState get initialState {
return initialState ?? JobListInitial();
}
final JobListRepository jobListRepository;
final UserAuthCubit userAuthCubit;
JobListCubit({this.jobListRepository, this.userAuthCubit})
: super(JobListInitial());
...
Hope this is what you were looking for. I am a novice and it took me a lot of time to find a solution...