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Global key is getting reused in navigator #10154
Description
This is happening when I pop the route and then push a new route which uses as same global key in the old route.
Here is a simple example:
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new GestureDetector(
onTap:() {
Navigator.push(context, new MaterialPageRoute(builder: (_) => new Company(0)));
},
child: new Text('go to company'));
}
}
class Company extends StatelessWidget {
static final _scaffoldKey = new GlobalKey<ScaffoldState>();
final int companyId;
Company(this.companyId);
@override
Widget build(BuildContext context) {
return new Scaffold(
key: _scaffoldKey,
body: new Column(children: [
new Text('Company $companyId'),
new GestureDetector(
onTap:() {
Navigator.pop(context);
Navigator.push(context,
new MaterialPageRoute(builder: (_) => new Company(companyId+1)));
},
child: new Text('next company')),
]
));
}
}Clicks "go to company" and then clicks "next company", you will see
I/flutter ( 8026): The following assertion was thrown building Company():
I/flutter ( 8026): Multiple widgets used the same GlobalKey.
I/flutter ( 8026): The key [LabeledGlobalKey<ScaffoldState>#33415169] was used by multiple widgets. The parents of
I/flutter ( 8026): those widgets were different widgets that both had the following description:
I/flutter ( 8026): Company()
I/flutter ( 8026): A GlobalKey can only be specified on one widget at a time in the widget tree.
It seems that the popped route did not remove the global key from the widget tree.
Activity
eseidelGoogle commentedon May 18, 2017
@Hixie would know.
Hixie commentedon May 18, 2017
When you pop a route, it animates away. While this is happening, the old route and the new route are both on the screen at the same time, and cannot share a global key.
123qws commentedon May 18, 2017
Thanks @Hixie !
The issue is resolved if you make
_scaffoldKeynon-static. I was wondering is this a proper way to assign a global key to theStatelessWidgetorState<T>for StatefulWidget?Hixie commentedon May 18, 2017
Usually I just skip using the key and use the Builder pattern instead. See the second code snippet here:
https://docs.flutter.io/flutter/material/Scaffold/of.html
123qws commentedon May 18, 2017
Thanks! Builder pattern looks good!
Roll engine to 6e6de94
Roll engine to 6e6de94 (#40394)
Roll engine 7ea9884..1b63444 (91 commits 🔥🔥🔥) (#40442)
Roll engine to 6e6de94 (flutter#40394)
Roll engine 7ea9884..1b63444 (91 commits 🔥🔥🔥) (flutter#40442)
github-actions commentedon Sep 4, 2021
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flutter doctor -vand a minimal reproduction of the issue.