[英]State or event not getting changed in flutter bloc
我按照以下方式定義了一個抽象的無狀態小部件
abstract class BaseStatelessWidget<T extends Bloc> extends StatelessWidget {
@override
Widget build(BuildContext context) {
if (shouldHideStatusBar) {
SystemChrome.setEnabledSystemUIOverlays([]);
}
return MultiBlocProvider(
providers: [
BlocProvider(
create: (context) {
BaseBloc baseBloc = getIt<BaseBloc>();
baseBloc.add(BaseEvent.networkListeningInitiated());
return baseBloc;
},
),
BlocProvider(
create: (context) => getImplementedBloc(context),
),
],
child: BlocListener<BaseBloc, BaseState>(
listener: _handleState,
child: buildScreen(context),
),
);
}
bool get shouldHideStatusBar => false;
_handleState(BuildContext context, BaseState state) {
// here different state will be managed
}
Widget buildScreen(BuildContext context);
T getImplementedBloc(BuildContext context);
}
另一個無狀態小部件 SigninPage 按照以下方式擴展它
class SigninPage extends BaseStatelessWidget<SigninBloc> {
@override
Widget buildScreen(BuildContext context) {
return Scaffold(
body: SingleChildScrollView(
child: SigninForm(),
),
resizeToAvoidBottomInset: true,
);
}
@override
bool get shouldHideStatusBar => true;
@override
SigninBloc getImplementedBloc(BuildContext context) {
return getIt<SigninBloc>();
}
}
為了這個問題,我從 SingInForm 類中刪除了冗余代碼,這里是代碼:
class SigninForm extends StatelessWidget {
@override
Widget build(BuildContext context) {
return PrimaryButton(
btnText: getString(context, StringKeys.signin),
onButtonClick: () => onSignin(context),
);
}
onSignin(BuildContext context) {
context.bloc<BaseBloc>().add(BaseEvent.changeLoaderStatus(visible: true)); => this is not working I tried to check if it is null. this is not null
context.bloc<SigninBloc>().add(SigninEvent.loginWithEmailPassword()); => this is working fine
}
}
這是我定義的 BaseBloc 類。 mapEventToState() 方法和 onTransition() 方法都沒有被調用。
import 'dart:async';
import 'package:connectivity/connectivity.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:freezed_annotation/freezed_annotation.dart';
import 'package:injectable/injectable.dart';
import 'package:refyne_app/domain/core/i_network_aware_facade.dart';
import 'package:refyne_app/domain/core/logger.dart';
import 'package:refyne_app/infrastructure/core/api_service/connectivity_status.dart';
part 'base_event.dart';
part 'base_state.dart';
part 'base_bloc.freezed.dart';
@injectable
class BaseBloc extends Bloc<BaseEvent, BaseState> {
INetworkAwareFacade _networkHandlerFacade;
BaseBloc(this._networkHandlerFacade)
: super(BaseState.initial(
isLoaderVisible: false,
));
@override
Stream<BaseState> mapEventToState(
BaseEvent event,
) async* {
yield* event.map(
networkListeningInitiated: (_) => _handleNetworkChange(), <== This one is causing the issue, if i remove this method. It works fine.
networkListeningStopped: (_) async* {},
changeLoaderStatus: (ChangeLoaderStatus value) async* {
logger.d('from bloc loader called with $value');
yield state.copyWith(isLoaderVisible: value.visible);
},
);
}
Stream<BaseState> _handleNetworkChange() async* {
await for (ConnectivityResult result
in _networkHandlerFacade.onConnectionChange()) { <== onConnectionChange will give you a stream
if (result == ConnectivityResult.none) {
yield state.copyWith(
connectionStatus: ConnectionStatus(
type: ConnectionType.NONE,
isworking: false,
));
} else {
bool isworking = await _networkHandlerFacade.checkConnection();
ConnectionType type = result == ConnectivityResult.mobile
? ConnectionType.MOBILE
: ConnectionType.WIFI;
yield state.copyWith(
connectionStatus: ConnectionStatus(type: type, isworking: isworking),
);
}
}
}
@override
void onError(Object error, StackTrace stackTrace) {
if (error is Exception) {
_handleException(error);
} else {
super.onError(error, stackTrace);
// TODO:: handle this exception scenario
}
}
_handleException(Exception e) {
print(e);
}
@override
void onTransition(Transition<BaseEvent, BaseState> transition) {
logger.d('from base bloc ${transition.event}');
logger.d('from base bloc ${transition.currentState}');
logger.d('from base bloc ${transition.nextState}');
super.onTransition(transition);
}
}
我正在嘗試訪問 BaseStatelessWidget 類中定義的基塊。 我定義的子塊工作正常,它也在發送事件。 我的問題是我無法更改父集團的狀態。 有人能告訴我我做錯了什么嗎? 任何幫助將不勝感激。 謝謝...
在掙扎了整整一天之后,現在我明白為什么會這樣了。 我直接在 mapEventToState 方法中處理流。 當我將流處理從 mapEventToState 移動到構造函數時,它工作正常。 希望它會幫助某人...
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