bloc_effects 0.3.0
bloc_effects: ^0.3.0 copied to clipboard
Cubit and Bloc abstractions and Flutter Widget that make it easy to add UI Effects to the BLoC state management.
SingleLiveEvent pattern implementation for Cubit and Bloc
Usage #
Lets take a look at how to use CubitWithEffects
to dispatch effects from CounterCubit
to
a CounterPage
and react on them with BlocEffectListener
.
ui_effect.dart #
abstract class UiEffect {}
class ShowBottomSheet implements UiEffect {
const ShowBottomSheet();
}
counter_cubit.dart #
class CounterCubit extends CubitWithEffects<int, UiEffect> {
CounterCubit() : super(0);
void increment() => emit(state + 1);
void onButtonPressed() => emitEffect(const ShowBottomSheet());
}
main.dart #
void main() => runApp(CounterApp());
class CounterApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: BlocProvider(
create: (_) => CounterCubit(),
child: CounterPage(),
),
);
}
}
counter_page.dart #
class CounterPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('Counter')),
body: BlocEffectListener<CounterCubit, SomeEffect, int>(
listener: (context, effect, state) {
if (effect is ShowBottomSheet) {
showBottomSheet<void>(
context: context,
builder: (c) =>
Material(
child: Container(
color: Colors.black12,
height: 150,
),
),
);
}
},
child: const Sizedbox(),
),
floatingActionButton: FloatingActionButton(
child: const Icon(Icons.upload),
onPressed: () => context.read<CounterCubit>().onButtonPressed(),
),
);
}
}
And also BlocWithEffectsObserver
can be useful. It extends BlocObserver
and add onEffect
callback to base observing features:
app_bloc_observer.dart #
class AppBlocObserver extends BlocWithEffectsObserver {
@override
void onEffect(BlocBase bloc, Object? effect) {
super.onEffect(bloc, effect);
debugPrint('Used effect: $effect');
}
// Other [BlocObserver] overrides
}