我不明白为什么这里不接受提供者。
我的 main.dart 看起来像这样。
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: ChangeNotifierProvider<ContentDS>(
builder: (_) => ContentDS(),
child: Content(),
)
);
}
}
Provider 在 Content Class 中完美运行。现在我使用此代码从内容移动到内容详细信息
Navigator.of(ctx).push(MaterialPageRoute(
builder: (context) =>
ContentDetails(viewedList: listElement),
))
在内容详细信息中,我只是想再次访问提供者
final ds = Provider.of<ContentDS>(context);
但这给了我以下错误
错误:在此 ContentDetails 小部件上方找不到正确的提供程序
要修复,请:
- 确保 Provider 是此 ContentDetails 小部件的祖先 * 向 Provider 提供类型 * 向 Consumer 提供类型 * 向 Provider.of() 提供类型 * 始终使用包导入。例如:
import 'package:my_app/my_code.dart'; * Ensure the correct
上下文`正在被使用。
内容详细信息代码
class ContentDetails extends StatefulWidget {
ToDoList viewedList;
ContentDetails({this.viewedList});
@override
_ContentDetailsState createState() => _ContentDetailsState();
}
class _ContentDetailsState extends State<ContentDetails> with SingleTickerProviderStateMixin{
bool isOpened = false;
AnimationController _animationController;
Animation<Color> _buttonColor;
Animation<double> _animateIcon;
Animation<double> _translateButton;
Curve _curve = Curves.easeOut;
double _fabHeight = 56.0;
initState() {
_animationController =
AnimationController(vsync: this, duration: Duration(milliseconds: 500))
..addListener(() {
setState(() {});
});
_animateIcon =
Tween<double>(begin: 0.0, end: 1.0).animate(_animationController);
_buttonColor = ColorTween(
begin: Colors.blue,
end: Colors.red,
).animate(CurvedAnimation(
parent: _animationController,
curve: Interval(
0.00,
1.00,
curve: Curves.linear,
),
));
_translateButton = Tween<double>(
begin: _fabHeight,
end: -14.0,
).animate(CurvedAnimation(
parent: _animationController,
curve: Interval(
0.0,
0.75,
curve: _curve,
),
));
super.initState();
}
@override
dispose() {
_animationController.dispose();
super.dispose();
}
animate() {
if (!isOpened) {
_animationController.forward();
} else {
_animationController.reverse();
}
isOpened = !isOpened;
}
@override
Widget build(BuildContext context) {
final ds = Provider.of<ContentDS>(context);
print(" ds.count ---> " + ds.count.toString());
if (widget.viewedList != null){
debugPrint(" widget.viewedList.primaryID ---> " + widget.viewedList.primaryID);
}else{
debugPrint(" It is null");
}
return
Hero(
tag: (widget.viewedList != null) ? widget.viewedList.primaryID : 'Hero',
child: Scaffold(
appBar: new AppBar(
backgroundColor: ListStatusHelper.getBgGenericColor(widget.viewedList?.status ?? ListStatus.NONE),
title: Text('${getListTitle()}'),
elevation: 0.0,
),
floatingActionButton: Wrap(
direction: Axis.vertical,
children: <Widget>[
transformWorks(edit(), 3),
transformWorks(save(), 2),
transformWorks(inbox(),1),
toggleButton()
],
),
body: Container(
color: ListStatusHelper.getBgGenericColor(widget.viewedList?.status ?? ListStatus.NONE),
child: const Text("Once Provider is available, need to work on this section");
),
),
);
}
Widget transformWorks(Widget btn, int pos){
return Transform(
transform: Matrix4.translationValues(
0.0,
_translateButton.value * pos,
0.0,
),
child: btn,
);
}
Widget inbox() {
return Container(
child: FloatingActionButton(
heroTag: null,
onPressed: null,
tooltip: 'Inbox',
elevation: 0.0,
child: Icon(Icons.inbox),
),
);
}
Widget edit() {
return Container(
child: FloatingActionButton(
heroTag: null,
onPressed: null,
tooltip: 'Edit',
elevation: 0.0,
child: Icon(Icons.edit),
),
);
}
Widget save() {
return Container(
child: FloatingActionButton(
heroTag: null,
onPressed: null,
tooltip: 'Save',
elevation: 0.0,
child: Icon(Icons.save),
),
);
}
Widget toggleButton(){
return FloatingActionButton(
heroTag: null,
backgroundColor: _buttonColor.value,
onPressed: animate,
tooltip: 'Toggle',
child: AnimatedIcon(
icon: AnimatedIcons.menu_close,
progress: _animateIcon,
),
);
}
String getListTitle() {
if (widget.viewedList != null) {
return widget.viewedList.listTitle;
} else {
return 'New List';
}
}
}
我是一名正在尝试学习 Flutter 的 iOS 开发人员,我认为 Provider 应该可用于属于导航流的所有类,而无需使用任何 DI。
帮助我意识到我错过了什么。在上述情况下的导航流的情况下应该如何使用 Provider。
提前致谢