我不确定如何实现 FutureBuilder
元素以及我的构建树中的其他非异步元素。我正在使用 Consumer
的事实监听 ChangeNotifierprovider
中的变化使事情有些复杂化。我可以同时使用提供者和 FutureBuilder 吗?在以下代码中,我需要访问的相关 future 是 socialProvider.currentavatar
和 socialProvider.currentname
在底部导航栏中。
Widget build(BuildContext context) {
var socialProvider = Provider.of<SocialProvider>(context);
return new MaterialApp(
home: new Scaffold(
body: _myPages[_selectedIndex],
bottomNavigationBar: BottomNavigationBar(
type: BottomNavigationBarType.fixed,
items: <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Home'),
),
BottomNavigationBarItem(
icon: Consumer<SocialProvider>(
builder: (context, socialProvider, child) {
return Image.network(socialProvider.currentavatar);
}),
title: Consumer<SocialProvider>(
builder: (context, socialProvider, child) {
return Text(socialProvider.currentname);
}),
),
],
currentIndex: _selectedIndex,
onTap: _onItemTapped,
),
),
);
}
这是我的 SocialProvider with ChangeNotifier
中的代码类(class)。 class SocialProvider with ChangeNotifier {
String currentname = loadCurrentName();
String currentavatar = loadCurrentAvatar();
loadCurrentName() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String currentname = await prefs.getString('currentname') ?? 'Anonymous';
return currentname;
}
loadCurrentAvatar() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String currentavatar = await prefs.getString('currentavatar') ?? "https://example.com/default.png";
return currentavatar;
}
}
如何实现 FutureBuilder 以便获取 socialProvider.currentname 和 socialProvider.currentavatar?
最佳答案
在 FutureBuilder 中包装你的脚手架。您可以使用 Future.wait
在 FutureBuilder 中运行 2 个 future 。由于您没有从 Snapshot 获取数据,因此您可以摆脱这些消费者,除非您计划更新这些字段。
Widget build(BuildContext context) {
var socialProvider = Provider.of<SocialProvider>(context);
return new MaterialApp(
home: FutureBuilder(
future: Future.wait([socialProvider.loadCurrentName(), socialProvider.loadCurrentAvatar()]),
builder: (context, snapshot) {
if (snapshot.hasData) {
return Scaffold(
body: _myPages[_selectedIndex],
bottomNavigationBar: BottomNavigationBar(
type: BottomNavigationBarType.fixed,
items: <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Home'),
),
BottomNavigationBarItem(
icon: Consumer<SocialProvider>(
builder: (context, socialProvider, child) {
return Image.network(snapshot.data[1]);
}),
title: Consumer<SocialProvider>(
builder: (context, socialProvider, child) {
return Text(snapshot.data[0]);
}),
),
],
currentIndex: _selectedIndex,
onTap: _onItemTapped,
),
);
} else if(snapshot.hasError) {
// handle error.
} else{
// handle loading.
}
}
),
);
}
class SocialProvider with ChangeNotifier {
String currentname = loadCurrentName();
String currentavatar = loadCurrentAvatar();
Future<String> loadCurrentName() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String currentname = await prefs.getString('currentname') ?? 'Anonymous';
return currentname;
}
Future<String> loadCurrentAvatar() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String currentavatar = await prefs.getString('currentavatar') ?? "https://example.com/default.png";
return currentavatar;
}
}
关于Flutter/Dart - 在我的构建中使用 FutureBuilder 和 Normal 非异步元素?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/63155903/