Multi BlocBuilder in Flutter

Question

I am a beginner in flutter and is there any examples or documentations which related to multi blocbuilder in one page by using flutter_bloc package in Flutter.

Answer 1

The latest flutter_bloc docs explain how to create a MultiBlocBuilder, when your Widget's builder relies on multiple BLOC's:

Builder(
  builder: (context) {
    final stateA = context.watch<BlocA>().state;
    final stateB = context.watch<BlocB>().state;
    final stateC = context.watch<BlocC>().state;

    // return a Widget which depends on the state of BlocA, BlocB, and BlocC
  }
);

The flutter_multi_bloc_builder somewhat simplifies this syntax (... does it?), its latest doc also describes how to do the same thing using that package:

final bloc1 = BlocProvider.of<MyBloc1>(context);
final bloc2 = BlocProvider.of<MyBloc2>(context);
final bloc3 = BlocProvider.of<MyBloc2>(context);

MultiBlocBuilder(
    blocs: [bloc1, bloc2, bloc3],
    builder: (context, states) {
        final state1 = states.get<MyBloc1State>();
        final state2 = states.get<MyBloc2State>();
        final state3 = states.get<MyBloc3State>();
        
        if (state1 is Loading || state2 is Loading || state3 is Loading) {
            return Text("Loading");
        } else {
            return Text("SHow some content");
        }
    }
);

Might have been more useful if some buildWhen or selector equivalent had been offered in this package?

I hope this answers the question.

Answer 2

BlocBuilder(), like any other Widgets, can be used multiple times. To use multiple of BlocBuilders in a screen, you just need to provide the needed Streamable (Bloc) on different BlocBuilder.