我有一个关于如何在Flutter中使用Streams和RxDart调用刷新指示符后重新加载列表的问题 .
这是我的,我的模型类:
class HomeState {
List<Event> result;
final bool hasError;
final bool isLoading;
HomeState({
this.result,
this.hasError = false,
this.isLoading = false,
});
factory HomeState.initial() =>
new HomeState(result: new List<Event>());
factory HomeState.loading() => new HomeState(isLoading: true);
factory HomeState.error() => new HomeState(hasError: true);
}
class HomeBloc {
Stream<HomeState> state;
final EventRepository repository;
HomeBloc(this.repository) {
state = new Observable.just(new HomeState.initial());
}
void loadEvents(){
state = new Observable.fromFuture(repository.getEventList(1)).map<HomeState>((List<Event> list){
return new HomeState(
result: list,
isLoading: false
);
}).onErrorReturn(new HomeState.error())
.startWith(new HomeState.loading());
}
}
我的小部件:
class HomePageRx extends StatefulWidget {
@override
_HomePageRxState createState() => _HomePageRxState();
}
class _HomePageRxState extends State<HomePageRx> {
HomeBloc bloc;
_HomePageRxState() {
bloc = new HomeBloc(new EventRest());
bloc.loadEvents();
}
Future<Null> _onRefresh() async {
bloc.loadEvents();
return null;
}
@override
Widget build(BuildContext context) {
return new StreamBuilder(
stream: bloc.state,
builder: (BuildContext context, AsyncSnapshot<HomeState> snapshot) {
var state = snapshot.data;
return new Scaffold(
body: new RefreshIndicator(
onRefresh: _onRefresh,
child: new LayoutBuilder(builder:
(BuildContext context, BoxConstraints boxConstraints) {
if (state.isLoading) {
return new Center(
child: new CircularProgressIndicator(
backgroundColor: Colors.deepOrangeAccent,
strokeWidth: 5.0,
),
);
} else {
if (state.result.length > 0) {
return new ListView.builder(
itemCount: snapshot.data.result.length,
itemBuilder: (BuildContext context, int index) {
return new Text(snapshot.data.result[index].title);
});
} else {
return new Center(
child: new Text("Empty data"),
);
}
}
}),
),
);
});
}
}
问题是当我从列表中执行pull刷新时,UI不刷新(服务器被调用,刷新指示符的动画也是),我知道问题与流有关但我不知道如何解决这个问题 .
预期结果:显示CircularProgressIndicator,直到加载数据
有帮助吗?谢谢
1 回答
您不应该更改
state
的实例 .您应该向observable提交一个新值 . 因此,收听
state
的StreamBuilder
将收到新值的通知 .这意味着您不能在内部拥有
Observable
实例,因为Observable
不需要Subject
.基本上这会将您的Bloc更改为以下内容:
另外,请注意
loadEvent
如何使用addError
除外 . 而不是推_1143976_与hasError: true
.