Pass parameter in BLoC pattern Flutter(Stream Controller) - flutter

Question

I am new to Flutter and not sure if this is the right method to follow. I am following YouTube tutorial to create a movie app using TMDB API and trying to pass 'genreId' from category.dart(comment below) to MovieBloc.dart. Is it possible to send the 'genreId'? If yes, how can I pass it? If not, what is the best way to do it?
Thank you
category.dart
final movieBloc = MovieBloc();
setState(() {
selectedGenre = genre.id;
movieBloc.eventSink.add(MovieControlAction.byGenre); // send genreId through here??
});
movie_bloc.dart
import 'dart:async';
import 'package:flutter_api/Model/movie.dart';
import 'package:flutter_api/Service/api_service.dart';
enum MovieControlAction { fetch, delete, byGenre, }
class MovieBloc {
final service = ApiService();
final _stateStreamController = StreamController<List<Movie>>();
StreamSink<List<Movie>> get _movieSink => _stateStreamController.sink;
Stream<List<Movie>> get movieStream => _stateStreamController.stream;
final _eventStreamController = StreamController<MovieControlAction>();
StreamSink<MovieControlAction> get eventSink =>
_eventStreamController.sink; //input
Stream<MovieControlAction> get _eventStream =>
_eventStreamController.stream; //output
MovieBloc() {
_eventStream.listen((event) async {
if (event == MovieControlAction.fetch) {
try {
var movies = await service.getNowPlayingMovie();
if (movies != null) {
_movieSink.add(movies);
} else {
_movieSink.addError('Null');
}
} on Exception catch (e) {
print(e);
_movieSink.addError('Something went wrong');
}
} else if (event == MovieControlAction.byGenre) {
var moviesByGenre = await service.getMovieByGenre(genreId);
if (moviesByGenre != null) {
_movieSink.add(moviesByGenre);
} else {
_movieSink.addError('Null');
}
}
});
}
void dispose() {
_stateStreamController.close();
_eventStreamController.close();
}
}

Answer 1

You can pass it to the MovieBloc like follows:
final movieBloc = MovieBloc(genreId: genre.id);
And then create a constructor within the MovieBloc class:
class MovieBloc {
final String genreId; // String, int, whatever type it is
MovieBloc({
required this.genreId,
});
}
If you want to use a real Bloc, you should extend the MovieBloc like this:
class MovieBloc extends Bloc<MovieEvent, MovieState> {}
Currently it's not looking like you are using the actual Bloc pattern. Please check the official Bloc documentation. I promise - it's super helpful.