| name | asyncredux-actions-no-state-change |
| description | Creates AsyncRedux (Flutter) actions that return null from reduce() to not change the state. Such actions can still do side effects, dispatch other actions, or do nothing. |
Actions That Don't Change State
In AsyncRedux, returning a new state from reducers is optional. When you don't need to
modify the application state, return null to keep the current state unchanged.
Basic Pattern
Return null from reduce() when no state modification is needed:
class MyAction extends ReduxAction<AppState> {
AppState? reduce() {
// Perform side effects here
return null; // State remains unchanged
}
}
Conditional State Updates
Only update state when certain conditions are met:
class GetAmount extends ReduxAction<AppState> {
Future<AppState?> reduce() async {
int amount = await getAmount();
if (amount == 0)
return null; // No change needed
else
return state.copy(counter: state.counter + amount);
}
}
Coordinating Other Actions
Actions that dispatch other actions but don't modify state directly:
class InitAction extends ReduxAction<AppState> {
AppState? reduce() {
dispatch(ReadDatabaseAction());
dispatch(StartTimersAction());
dispatch(TurnOnListenersAction());
return null; // This action doesn't change state itself
}
}
Triggering External Services
Call external services without modifying app state:
class SendNotification extends ReduxAction<AppState> {
final String message;
SendNotification(this.message);
Future<AppState?> reduce() async {
await notificationService.send(message);
return null;
}
}
Navigation Actions
Trigger navigation as a side effect:
class GoToSettings extends ReduxAction<AppState> {
AppState? reduce() {
dispatch(NavigateAction.pushNamed('/settings'));
return null;
}
}
Key Points
- Actions that do return a new state can also do side effects and dispatch other actions.
- Return type matters: Use
AppState? for sync, Future<AppState?> for async
- Null means no change: The store keeps its current state
References
URLs from the documentation:
