Currently I'm working with BLoCs in Flutter and I've got a question about multiple streams within a Bloc.
For example when a screen has got multiple widgets which should depend on the Bloc. I could wrap the whole screen in the StreamBuilder, but then every time all widgets would be rebuilt.
The example bloc:
class TestBloc {
final StreamController _dataController = StreamController<String>();
final StreamController _appBarTitleController = StreamController<String>();
TestBloc();
Stream<String> get appBarTitle => _appBarTitleController.stream;
Stream<DataState> get data => _dataController.stream;
void fetchData(String path) async {
_dataController.sink.add(PokemonDataLoading());
Data data = await _getData();
_dataController.sink.add(Loaded(data));
_appBarTitleController.sink.add(data.name);
}
Future<Data> _getData(String path) async {
return await _dataRepository.fetchData(path);
}
void dispose() {
_dataController.close();
_appBarTitleController.close();
}
}
On the example build method you can see two different StreamBuilders, one for the app bar title and one for the content. Of course I could wrap them in this example into one StreamBuilder, but sometimes this isn't easily possible. They may depend on other data or user interactions.
@override
Widget build(BuildContext context) {
_testBloc.fetchData();
return ScaffoldWithSafeArea(
title: StreamBuilder(
stream: _testBloc.appBarTitle,
builder: (context, AsyncSnapshot<String> snapshot) {
if (snapshot.hasData) {
return Text(snapshot.data);
}
return Text("Test");
},
),
child: StreamBuilder<DataState>(
stream: _testBloc.data,
builder: (context, AsyncSnapshot<DataState> snapshot) {
DataState state = snapshot.data;
if (state is DataInitial) {
return _buildLoading();
} else if (state is DataLoaded) {
return _buildContent(state.data);
}
return _buildLoading();
},
),
);
}
Is there maybe a better solution for multiple Streams on one screen? I use a lot of boilerplate code here and would like to avoid this.