value_cubit

Description:

value cubit

A dart package that helps to implement basic states for BLoC library to perform, load and fetch data.




Features #

Provides all necessary states for data : init, waiting, value/no value and error states (from value_state),
A ValueCubit class to simplify Cubit subclassing,
A RefreshValueCubit class like ValueCubit with refreshing capabilities,
Some helpers perform (an extension on Cubit) to emit intermediate states while an action is intended to update state : the same state is reemitted with attribute refreshing at true.

Usage #
This example shows how different value states from this library help developpers to show load step data widgets.
class CounterCubit extends ValueCubit<int> {
var _value = 0;

// Put your WS call that can be refreshed
Future<int> _getCounterValueFromWebService() async => _value++;

Future<void> increment() => perform(() async {
// [perform] generate intermediate or final states such as PendingState,
// concrete subclass of ReadyState with right [ReadyState.refreshing] value
// or ErrorState if an error is raised.
final result = await _getCounterValueFromWebService();

emit(ValueState(result));
});

void clear() {
_value = 0;
emit(const PendingState());
}
}

class MyHomePage extends StatelessWidget {
const MyHomePage({super.key});

@override
Widget build(BuildContext context) {
final theme = Theme.of(context);

return BlocBuilder<CounterCubit, BaseState<int>>(builder: (context, state) {
return Scaffold(
appBar: AppBar(
title: const Text('Flutter Demo Home Page'),
),
body: DefaultTextStyle(
style: const TextStyle(fontSize: 24),
textAlign: TextAlign.center,
child: state is ReadyState<int>
? Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
if (state.refreshing) const LinearProgressIndicator(),
const Spacer(),
if (state.hasError)
Text('Expected error.',
style: TextStyle(color: theme.colorScheme.error)),
if (state is WithValueState<int>) ...[
if (state.hasError)
const Text('Previous counter value :')
else
const Text('Actual counter value :'),
Text(
state.value.toString(),
style: theme.textTheme.headlineMedium,
),
],
if (state is NoValueState<int>) const Text('No Value'),
const Spacer(),
],
)
: const Center(child: CircularProgressIndicator()),
),
floatingActionButton: state is! ReadyState<int>
? null
: FloatingActionButton(
onPressed: state.refreshing
? null
: context.read<CounterCubit>().increment,
tooltip: 'Increment',
child: state.refreshing
? SizedBox.square(
dimension: 20,
child: CircularProgressIndicator(
color: theme.colorScheme.onPrimary))
: const Icon(Icons.refresh)),
);
});
}
}
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The whole code of this example is available in example.
If your cubit is only a getter with the need to refresh your cubit state, you can simplify the implementation ValueCubit with RefreshValueCubit.
class CounterCubit extends RefreshValueCubit<int> {
var _value = 0;

// Put your WS call that can be refreshed
Future<int> _getCounterValueFromWebService() async => _value++;

@override
Future<void> emitValues() async {
final result = await _getCounterValueFromWebService();

emit(ValueState(result));
}
}
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Update your value (increment in our example) by calling myCubit.refresh().
Feedback #
Please file any issues, bugs or feature requests as an issue on the Github page.