如何解决对多个页面使用相同的 riverpod 状态提供程序
我正在使用提供程序进行状态管理(实际上是 riverpod) 在我的项目中,我有一个 tabview 并使用每个选项卡作为一个类别,每个选项卡都显示新闻列表。 tabview 大小不固定,我对所有选项卡使用相同的页面并将类别 ID 传递给页面。
问题是 newsProvider 总是保留最后一个类别 id 并且所有页面都显示相同的新闻列表。 我可以为每个页面单独列出谁的 newsProvider 列表?
//create tabview in my stateFullWidget
@override
Widget build(BuildContext context) {
return Scaffold(
body: DefaultTabController(
length: europeanCountries.length,// europeanCountries has dynamic size
child: new Scaffold(
appBar: new AppBar(
flexibleSpace: new Column(
children: [
new TabBar(
tabs: europeanCountries.map<Widget>((e) => getTab(e,FontAwesomeIcons.newspaper)).toList()),],),// dynamically create NewsList and pass category id
body: TabBarView(children: europeanCountries.map((catItem) => NewsList(category: Category(title: catItem.title,id:catItem.id))).toList()),)
)
}
class NewsList extends StatefulWidget {
Category category;
NewsList({this.category});
@override
State<StatefulWidget> createState() {
return _NewsListState(category:category);
}
}
class _NewsListState extends State<NewsList> with AutomaticKeepAliveClientMixin<NewsList> {
Category category;
_NewsListState({this.category});
@override
void initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) {
context.read(newsProvider).getNewsList(category.id);
});
}
@override
Widget build(BuildContext context) {
return Consumer(builder: (ctx,watch,child) {
return watch(newsProvider.state).map(
init: (value) {
return Container();
},loading: (value) {
return Container(
child: Center(
child: CircularProgressIndicator(),);
},success: (value) {
return Container(child: getNewsItem(value.newsList));
},serverError: (value) {
return Container();
},);
});
}
@override
bool get wantKeepAlive => true;
}
final newsProvider = StateNotifierProvider.autoDispose<NewsListNotifier>((ref) {
var newsService = ref.watch(newsServiceProvider);
return NewsListNotifier(newsService);
});
class NewsListNotifier extends StateNotifier<NewsListState> {
final NewsService serviceRepository;
NewsListNotifier(this.serviceRepository) : super(NewsListState.init());
getNewsList(int catID) async {
state = NewsListState.loading();
DataResponse request = await serviceRepository.getNewsList(catID);
request.maybeWhen(
success: (value) {
if (value.data != null) {
state = NewsListState.success(newsList: value.data);
}
},error: (error) {
state = NewsListState.serverError(error);
},orElse: () {},);
}
}
解决方法
我终于找到了答案。谢谢@EdwynZN 通过使用 family 关键字,我可以为每个类别创建一些类似家庭的东西
class NewsList extends StatefulWidget {
Category category;
NewsList({this.category});
@override
State<StatefulWidget> createState() {
return _NewsListState(category:category);
}
}
class _NewsListState extends State<NewsList> with AutomaticKeepAliveClientMixin<NewsList> {
Category category;
_NewsListState({this.category});
@override
void initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) {
// add category.id to newsProvider,instead of getNewsList()
context.read(newsProvider(category.id)).getNewsList();
});
}
@override
Widget build(BuildContext context) {
return Consumer(builder: (ctx,watch,child) {
//newsProvider(category.id) just listen to specific category id and not listen to all ids
return watch(newsProvider(category.id).state).map(
init: (value) {
return Container();
},loading: (value) {
return Container(
child: Center(
child: CircularProgressIndicator(),),);
},success: (value) {
return Container(child: getNewsItem(value.newsList));
},serverError: (value) {
return Container();
},);
});
}
@override
bool get wantKeepAlive => true;
}
//using family here and pass <My State,Category id>
final newsProvider = StateNotifierProvider.family<NewsListNotifier,int>((ref,catID) {
var newsService = ref.watch(newsServiceProvider);
return NewsListNotifier(newsService,catID);
});
class NewsListNotifier extends StateNotifier<NewsListState> {
final NewsService serviceRepository;
int catID;
NewsListNotifier(this.serviceRepository,this.catID) : super(NewsListState.init());
getNewsList() async {
state = NewsListState.loading();
DataResponse request = await serviceRepository.getNewsList(catID,page,20);
request.maybeWhen(
success: (value) {
if (value.data != null) {
state = NewsListState.success(newsList: value.data);
}
},error: (error) {
state = NewsListState.serverError(error);
},orElse: () {},);
}
}
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