darshankawar
commented
1 year ago Verified on latest versions using the example code provided and can see the same reported behavior.
Open justinmc opened 1 year ago
darshankawar
commented
1 year ago Verified on latest versions using the example code provided and can see the same reported behavior.
ValentinVignal
commented
1 year ago This might come from https://github.com/flutter/flutter/issues/119677 and be a duplicate
justinmc
commented
1 year ago I think you're right!
Amir-P
commented
1 year ago @ValentinVignal @darshankawar The problem is not in GoRouter.canPop(). In fact it's working correctly since Navigator.canPop() returns false in that moment too. You can validate it yourself:
final rootKey = GlobalKey<NavigatorState>();
class _MyAppState extends State<_MyApp> {
final GoRouter _router = GoRouter(
navigatorKey: rootKey,
...
);
void _routerChanged() {
print(
'GoRouter changed. Location: ${_router.location}. canPop? ${_router.canPop()}. nav.canPop? ${rootKey.currentState?.canPop()}');
SchedulerBinding.instance.addPostFrameCallback((Duration duration) {
print(
'After the post frame callback. Location: ${_router.location}. canPop? ${_router.canPop()}. nav.canPop? ${rootKey.currentState?.canPop()}');
});
}
}
chunhtai
commented
1 year ago it is that the goRouter notify its listener one frame early, the route change will take one frame to propagate the change to navigator before its canPop will change.
P1Rh0
commented
2 weeks ago Hey :) Is there any update on this? I'm trying to add a back button to pages where canPop is true - for the first route in a stack I'm getting canPop = false on first render.
Eg for Sub routes a b and c...
initial route /a correctly returns canPop = false
navigating to /a/b also returns canPop = false on first render so the back button isn't displayed (incorrectly as obviously we can go back to /a now)
Navigating another level to /a/b/c we see the back button is visible as canPop = true (I assume due to now picking up on the previous route?)
Clicking the back button to go back to /a/b then puts you back to the second screen but now canPop = true on first render and the back button correctly appears
leanang
commented
1 week ago Hey :) Is there any update on this? I'm trying to add a back button to pages where canPop is true - for the first route in a stack I'm getting
canPop = falseon first render. Eg for Sub routes a b and c... initial route/acorrectly returnscanPop = falsenavigating to/a/balso returnscanPop = falseon first render so the back button isn't displayed (incorrectly as obviously we can go back to/anow) Navigating another level to/a/b/cwe see the back button is visible ascanPop = true(I assume due to now picking up on the previous route?) Clicking the back button to go back to/a/bthen puts you back to the second screen but nowcanPop = trueon first render and the back button correctly appears
class NaviBackButton extends StatefulWidget {
const NaviBackButton({
super.key,
});
@override
State<NaviBackButton> createState() => _NaviBackButtonState();
}
class _NaviBackButtonState extends State<NaviBackButton> {
late bool _canPop = context.canPop();
@override
Widget build(BuildContext context) {
// https://github.com/flutter/flutter/issues/124637
SchedulerBinding.instance.addPostFrameCallback((Duration duration) {
setState(() {
_canPop = context.canPop();
});
});
return IconButton(
onPressed: _canPop ? () => context.pop() : null,
icon: const Icon(Icons.chevron_left, size: 24),
);
}
}
GoRouter's canPop method gives out of date results until the following frame after the navigation.
Steps to reproduce
Expected: When GoRouter's listener is called, its
canPopis true, because there are two routes on the stack.Actual: GoRouter's listener is called, and the
locationis correct, butcanPopis still out of date and gives false. After a post frame callback, it is up to date and returns true.Example app
```dart // Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'package:flutter/scheduler.dart'; import 'package:go_router/go_router.dart'; import 'package:flutter/material.dart'; import 'package:flutter/services.dart'; void main() => runApp(_MyApp()); class _MyApp extends StatefulWidget { @override State<_MyApp> createState() => _MyAppState(); } class _MyAppState extends State<_MyApp> { final GoRouter _router = GoRouter( routes:Filed this issue after discovering while working on predictive back and talking to @chunhtai offline.