Error thrown on navigator pop until : "!_debugLocked': is not true."
DartFlutterNavigatorDart Problem Overview
When popping a screen navigating to other one by clicking on the showBottomSheet, this error is thrown through the following code . I cant get why this is occurring.
class _CheckoutButtonState extends State<_CheckoutButton> {
final GlobalKey<ScaffoldState> _globalKey = GlobalKey();
final DateTime deliveryTime = DateTime.now().add(Duration(minutes: 30));
final double deliveryPrice = 5.00;
@override
Widget build(BuildContext context) {
SubscriptionService subscriptionService =
Provider.of<SubscriptionService>(context);
CheckoutService checkoutService = Provider.of<CheckoutService>(context);
return Container(
height: 48.0,
width: MediaQuery.of(context).size.width * 0.75,
child: StreamBuilder(
stream: subscriptionService.subscription$,
builder: (_, AsyncSnapshot<Subscription> snapshot) {
if (!snapshot.hasData) {
return Text("CHECKOUT");
}
final Subscription subscription = snapshot.data;
final List<Order> orders = subscription.orders;
final Package package = subscription.package;
num discount = _getDiscount(package);
num price = _totalPriceOf(orders, discount);
return StreamBuilder<bool>(
stream: checkoutService.loading$,
initialData: false,
builder: (context, snapshot) {
bool loading = snapshot.data;
return ExtendedFloatingActionButton(
loading: loading,
disabled: loading,
action: () async {
checkoutService.setLoadingStatus(true);
final subscription =
await Provider.of<SubscriptionService>(context)
.subscription$
.first;
try {
await CloudFunctions.instance.call(
functionName: 'createSubscription',
parameters: subscription.toJSON);
final bottomSheet =
_globalKey.currentState.showBottomSheet(
(context) {
return Container(
width: MediaQuery.of(context).size.width,
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
colors: [
Theme.of(context).scaffoldBackgroundColor,
Theme.of(context).primaryColor,
Theme.of(context).primaryColor,
],
stops: [-1.0, 0.5, 1.0],
),
),
child: Column(
children: <Widget>[
Expanded(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Padding(
padding:
const EdgeInsets.only(bottom: 16.0),
child: Text(
"Thank you for your order",
textAlign: TextAlign.center,
style: Theme.of(context)
.textTheme
.display1,
),
),
SvgPicture.asset(
'assets/images/thumb.svg',
height: 120.0,
width: 100.0,
)
// CircleAvatar(
// radius: 40.0,
// backgroundColor: Colors.transparent,
// child: Icon(
// Icons.check,
// color: Theme.of(context)
// .textTheme
// .display1
// .color,
// size: 80.0,
// ),
// ),
],
),
),
Container(
width:
MediaQuery.of(context).size.width * 0.9,
height: 72.0,
padding: EdgeInsets.only(bottom: 24),
child: ExtendedFloatingActionButton(
text: "ORDER DETAILS",
action: () {
Navigator.of(context).pop();
},
),
),
],
),
);
},
);
bottomSheet.closed.then((v) {
Navigator.of(context)
.popUntil((r) => r.settings.isInitialRoute);
});
} catch (e) {
print(e);
final snackBar =
SnackBar(content: Text('Something went wrong!'));
Scaffold.of(context).showSnackBar(snackBar);
}
},
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
"CHECKOUT ",
style: Theme.of(context)
.textTheme
.display4
.copyWith(color: Colors.white),
),
Text(
"EGP " +
(price + (orders.length * deliveryPrice))
.toStringAsFixed(2),
style: Theme.of(context)
.textTheme
.display4
.copyWith(color: Theme.of(context).primaryColor),
),
],
),
);
});
},
),
);
}
num _totalPriceOf(List<Order> orders, num discount) {
num price = 0;
orders.forEach((Order order) {
List<Product> products = order.products;
products.forEach((Product product) {
price = price + product.price;
});
});
num priceAfterDiscount = price * (1 - (discount / 100));
return priceAfterDiscount;
}
num _getDiscount(Package package) {
if (package == null) {
return 0;
} else {
return package.discount;
}
}
}
Error :
>══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (24830): The following assertion was thrown building Navigator-[GlobalObjectKey<NavigatorState>
I/flutter (24830): _WidgetsAppState#90d1f](dirty, state: NavigatorState#6b2b6(tickers: tracking 1 ticker)):
I/flutter (24830): 'package:flutter/src/widgets/navigator.dart': Failed assertion: line 1995 pos 12: '!_debugLocked':
I/flutter (24830): is not true.
I/flutter (24830): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (24830): more information in this error message to help you determine and fix the underlying cause.
I/flutter (24830): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (24830): https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter (24830): When the exception was thrown, this was the stack:
Dart Solutions
Solution 1 - Dart
Instead of giving you a direct answer, I'm going to walk you through how I thought about this when I saw the question, in the hope that it'll help you in the future.
Let's take a look at the assertion. It says Failed assertion: line 1995 pos 12: '!_debugLocked': I/flutter (24830): is not true.. Hmm, interesting. Let's take a look at that line of code.
> assert(!_debugLocked);
Well, that doesn't give me much more information, let's look at the variable.
> bool _debugLocked = false; // used to prevent re-entrant calls to push, pop, and friends
That's better. It's there to prevent re-entrant calls to push, pop, etc (by that it means that it doesn't want you calling 'push', 'pop', etc from within a call to 'push', 'pop'). So let's trace that back to your code.
This seems like the likely culprit:
bottomSheet.closed.then((v) {
Navigator.of(context)
.popUntil((r) => r.settings.isInitialRoute);
});
I'm going to skip a step here and use deductive reasoning instead - I'm betting that the closed future is finished during a pop. Go ahead and confirm that by reading the code if you feel like it.
So, if the issue is that we're calling pop from within a pop function, we need to figure out a way to defer the call to pop until after the pop has completed.
This becomes quite simple - there's two ways to do this. The simple way is to just use a delayed future with zero delay, which will have dart schedule the call as soon as possible once the current call stack returns to the event loop:
Future.delayed(Duration.zero, () {
Navigator. ...
});
The other more flutter-y way of doing it would be to use the Scheduler to schedule a call for after the current build/render cycle is done:
SchedulerBinding.instance.addPostFrameCallback((_) {
Navigator. ...
});
Either way should eliminate the problem you're having.
Another option is also possible though - in your ExtendedFloatingActionButton where you call pop:
ExtendedFloatingActionButton(
text: "ORDER DETAILS",
action: () {
Navigator.of(context).pop();
},
),
you could instead simply do the call to Navigator.of(context).popUntil.... That would eliminate the need for the doing anything after bottomSheet.closed is called. However, depending on whatever else you might or might not need to do in your logic this may not be ideal (I can definitely see the issue with having the bottom sheet set off a change to the main part of the page and why you've tried to make that happen in the page's logic).
Also, when you're writing your code I'd highly recommend separating it into widgets - for example the bottom sheet should be its own widget. The more you have in a build function, the harder it is to follow and it can actually have an effect on performance as well. You should also avoid using GlobalKey instances wherever possible - you can generally either pass objects (or callbacks) down if it's only through a few layers, use the
Solution 2 - Dart
For those who are invoking the Navigator as part of the build process. I found that it will intermittently throwing asserting error on the debugLocked
I avoided this issue by wrapping with a addPostFrameCallback:
WidgetsBinding.instance.addPostFrameCallback((_) {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (_) => MyPage()));
});
Solution 3 - Dart
Add Some Delay Then Try to do this Your Problem will be Solved :
Future.delayed(const Duration(milliseconds: 500), () {
// Here you can write your code
setState(() {
Navigator.of(context).pushAndRemoveUntil(
MaterialPageRoute(builder: (context) => SetCategory()),
(route) => false);
});
});
Solution 4 - Dart
I had this same issue any answer not worked for me and this error doesn't explain any thing.
After going each line code i found that we cannot launch any state in build method like this
@override
Widget build(BuildContext context) {
var viewmodel = Provider.of<ViewModel>(context);
Navigator.of(context).push(MaterialPageRoute(builder:
(context)=>CreateItemPage(viewmodel.catalogData))); // this is way i was getting error.
return Scaffold();
}
I was getting error in CreateItemPage screen because of that line.
Solution of this issue create button which call this line Navigator.of(context).push(MaterialPageRoute(builder: (context)=>CreateItemPage(viewmodel.catalogData)));
Solution 5 - Dart
For me, it was coming because I created a cycle of pushes that was causing this error. For example,
In the Initial route which was /loading the code was pushing /home
class _LoadingState extends State<Loading> {
void getTime() async {
// DO SOME STUFF HERE
Navigator.pushNamed(context, '/home');
}
@override
void initState() {
super.initState();
getTime();
}
And in the /home initState I was pushing /loading creating a cycle.
class _HomeState extends State<Home> {
@override
void initState() {
super.initState();
Navigator.pushNamed(context, '/loading');
}
Solution 6 - Dart
I had similar error, like a dialog box which had a logout button, which when pressed goes to login screen, but an _debugLocked error occurs, so I used
Navigator.of(context).pushNamedAndRemoveUntil('/screen4', (Route<dynamic> route) => false);
This removes all routes in the stack so that user cannot go back to the previous routes after they have logged out.
Setting (Route<dynamic> route) => false will make sure that all routes before the pushed route are removed.
I don't know if this is the "real" solution but it helped me as a beginner to Flutter.
Solution 7 - Dart
For people encountering this issue while using bloc, make sure you are using navigation in a BlocListener (or BlocConsumer's listener). In my case I was using Navigator inside BlocBuilder. I am new to Flutter/Bloc and the accepted answer resolved the problem, but was not the proper solution. Switching my BlocBuilder to a BlocConsumer allowed for me to navigate during specific states.
Example of using BlocConsumer, navigate when state is 'LoginSuccess':
BlocConsumer<LoginBloc, LoginState>(
listener: (BuildContext context, state) {
if (state is LoginSuccess) {
Navigator.of(context).pushReplacement(
// Add your route here
PageRouteBuilder(
pageBuilder: (_, __, ___) => BlocProvider.value(
value: BlocProvider.of<NavigationBloc>(context),
child: HomeScreen(),
),
),
);
}
},
// Only build when the state is not LoginSuccess
buildWhen: (previousState, state) {
return state is! LoginSuccess;
},
// Handle all states other than LoginSuccess here
builder: (BuildContext context, LoginState state) {
if (state is LoginLoading) {
return Center(child: CircularProgressIndicator());
} else .....
Solution 8 - Dart
In resume, you just need to remove it from your initState. I would recomend extend the class with AfterLayout and inside the afterFirstLayout you can redirect it to the page you want. This will garantee that everything is ok before routing.
See bellow the steps: Add to pubspec: after_layout: ^1.0.7+2
Then, You will extend it to the class you want to use. In my case was a statefull widget named HomePage. So it will looks like:
class HomePage extends StatefulWidget {
@override
HomePageState createState() => HomePageState();
} //no changes here
class HomePageState extends State<HomePage> with AfterLayoutMixin<HomePage> {
//the with AfterLayoutMixin<pageName> is the only thing you need to change.
Now, you need to implement a method called afterlayout, that will be executed after the build is completed.
@override
Future<void> afterFirstLayout(BuildContext context) {
//your code here safetly
}
You can find information here: https://pub.dev/packages/after_layout
Solution 9 - Dart
For those that still have the same issue, this help me to solve it.
navigationService.popUntil((_) => true);
navigationService.navigateTo(
'authentication',
);
basically i wait until the navigation finish setting everything and then call the navigateTo.
Solution 10 - Dart
I got this error because my initialRoute was /login. However, the initialRoute is required to be /.
> If the route name starts with a slash, then it is treated as a "deep link", and before this route is pushed, the routes leading to this one are pushed also. For example, if the route was /a/b/c, then the app would start with the four routes /, /a, /a/b, and /a/b/c loaded, in that order.
Here is a link to the docs for reference.
Solution 11 - Dart
I am using flutter version 2.3.3
I also faced this issue when i try to pop back into my home screen from a second screen with command Navigator.pop(context)
I solved this issue by replacing this line of code with Navigator.of(context).pop(context)
It worked fine for me hope it hepls