从v7.2.1迁移到flatter_bloc v8.0.0后，不会触发flatter_block事件

Question

我尝试迁移flatter_bloc v8.0.0。在我阅读了文档后，我知道我需要将mapEventToState迁移到on。之后我没有收到错误，但_getMonks事件不是触发器。这是我的密码。有什么我错过的吗？

class MonkBloc extends Bloc<MonkEvent, MonkState> {
final MonkRespository monkRespository;
late List<Monk> monks;
MonkBloc({required this.monkRespository}) : super(MonkInitial()) {
on<GetMonksEvent>((event, emit) => _getMonks);
on<MonkSearchEvent>((event, emit) => _searchMonks);
}
Stream<MonkState> _getMonks(Emitter<MonkState> emit) async* {
emit(MonkLoading());
try {
final List<Monk> monks = await monkRespository.fetchMonks();
emit(MonkLoaded(monks: monks));
} catch (e) {
emit (MonkError(error: (e.toString())));
}
}
Stream<MonkState> _searchMonks(String query, Emitter<MonkState> emit) async* {
emit(MonkLoading());
try {
final List<Monk> monks = await monkRespository.searchMonks(query);
emit(MonkLoaded(monks: monks));
} catch (e) {
emit(MonkError(error: (e.toString())));
}
}
}
class MonkScreen extends StatefulWidget {
static const routeName = '/monk';
final String? title;
final MonkScreenMode? screenMode;
const MonkScreen({Key? key, this.title, this.screenMode}) : super(key: key);
@override
State<MonkScreen> createState() => _MonkScreenState();
}
class _MonkScreenState extends State<MonkScreen> {
_loadMonks() async {
BlocProvider.of<MonkBloc>(context).add(const GetMonksEvent()); 
}   
@override
void initState() {
super.initState();
_loadMonks();
}
@override
Widget build(BuildContext context) {
return BaseWidget(
child: Scaffold(
backgroundColor: Theme.of(context).backgroundColor,
appBar: AppBar(
centerTitle: true,
backgroundColor: Theme.of(context).backgroundColor,
elevation: 0,
title: AutoSizeText(
widget.title!,
style: Theme.of(context).appBarTheme.titleTextStyle,
),
leading: IconButton(
onPressed: () {
Navigator.pop(context);
},
icon: Icon(
Icons.arrow_back,
color: Theme.of(context).primaryIconTheme.color!,
),
),
actions: [
IconButton(
onPressed: () {
showSearch(
context: context,
delegate: MonkSearch(screenMode: widget.screenMode!));
},
icon: Icon(
Icons.search,
color: Theme.of(context).primaryIconTheme.color!,
),
),
],
),
body: BlocBuilder<MonkBloc, MonkState>(
builder: (BuildContext context, MonkState monkState) {
if (monkState is MonkError) {
return const SomethingWentWrongScreen();
} else if (monkState is MonkLoaded) {
return listViewBuilder(
context, monkState.monks, widget.screenMode!);
}
return const Center(
child: CircularProgressIndicator(),
);
},
),
),
);
}
}

Answer 1

这就是我迁移代码的方式。以防有人需要。

class MonkBloc extends Bloc<MonkEvent, MonkState> {
final MonkRespository monkRespository;
late List<Monk> monks;
MonkBloc({required this.monkRespository}) : super(MonkInitial()) {
on<GetMonksEvent>((event, emit) async {
await _getMonks(emit);
});
on<MonkSearchEvent>((event, emit) async {
await _searchMonks(event.query, emit);
});
}
Future<void> _getMonks(Emitter<MonkState> emit) async {
emit(MonkLoading());
try {
final List<Monk> monks = await monkRespository.fetchMonks();
emit(MonkLoaded(monks: monks));
} catch (e) {
emit (MonkError(error: (e.toString())));
}
}
Future<void> _searchMonks(String query, Emitter<MonkState> emit) async 
{
emit(MonkLoading());
try {
final List<Monk> monks = await monkRespository.searchMonks(query);
emit(MonkLoaded(monks: monks));
} catch (e) {
emit(MonkError(error: (e.toString())));
}
}
}

Answer 2

class APIBloc extends Bloc<APIEvents, APIState> {
//
final APIRepo apiRepo;
APIBloc({required this.apiRepo}) : super(APIInitState()) {
on<APIEvents>(_addToValue);
}
Future<void> _addToValue(APIEvents event, Emitter<APIState> emit) async {
print("onEvent");
emit(APILoading());
emit.forEach(
Stream.fromFuture(_callAPI(event).catchError((onError) {
return onError;
})), onData: (value) {
if (value is Response)
return APILoaded(response: value as Response);
else {
return value as APIListError;
}
});
}
Future<Object> _callAPI(APIEvents event) async {
try {
if (event is FetchDashBoard) {
return await apiRepo.getDashboardData(event.requestParams);
} else if (event is DoLogin) {
return await apiRepo.doLogin(event.requestParams);
} else {
throw (APIListError(
error: NoInternetException('No Internet'),
));
}
} on SocketException {
throw (APIListError(
error: NoInternetException('No Internet'),
));
} on HttpException {
throw (APIListError(
error: NoServiceFoundException('No Service Found'),
));
} on FormatException {
throw (APIListError(
error: InvalidFormatException('Invalid Response format'),
));
} catch (e) {
throw (APIListError(
error: UnknownException('Unknown Error'),
));
}
}
}

如果需要更多澄清代码，请访问下面的网站。https://flutterlearneasyway.blogspot.com/2021/11/flutter-bloc-pattern-800-call-api.html

Answer 3

这里有一个拼写错误。

on<GetMonksEvent>((event, emit) => _getMonks);

必须使用args调用_getMonks，或者只传递事件侦听器本身：

使用这个

on<GetMonksEvent>((event, emit) => _getMonks(event, emit));

或者更好的

on<GetMonksEvent>(_getMonks);