我有一个 firebase 驱动的 Flutter 应用程序,它可以运行但会抛出错误。
如我所料,当应用程序打开时,用户必须使用电子邮件和密码登录,如果登录成功,他们将看到一个名为 WelcomeScreen 的新 View 。
发生了什么,用户在登录后被带到欢迎屏幕,但我收到以下错误
[VERBOSE-2:ui_dart_state.cc(186)] Unhandled Exception: This widget has been unmounted, so the State no longer has a context (and should be considered defunct).
Consider canceling any active work during "dispose" or using the "mounted" getter to determine if the State is still active.
#0 State.context.<anonymous closure> (package:flutter/src/widgets/framework.dart:1088:9)
#1 State.context (package:flutter/src/widgets/framework.dart:1094:6)
#2 _AuthScreenState.initState.<anonymous closure> (package:autos_latinos/screens/auth_screen.dart:81:35)
#3 _rootRunUnary (dart:async/zone.dart:1362:47)
#4 _CustomZone.runUnary (dart:async/zone.dart:1265:19)
#5 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1170:7)
#6 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:341:11)
#7 _DelayedData.perform (dart:async/stream_impl.dart:591:14)
#8 _StreamImplEvents.handleNext (dart:async/stream_impl.dart:706:11)
#9 _PendingEvents.schedule.<anonymous closur<…>
它似乎指向我用来跟踪来自 firebase 的 authStateChanges 的代码中的这一部分:
FirebaseAuth.instance.authStateChanges().listen((User user) {
if (user == null) {
print('User is currently signed out!');
if(AuthScreen.id != '/AuthScreen'){
Navigator.pushReplacement(context, MaterialPageRoute(builder: (BuildContext context) => AuthScreen()));
}else{
print("Already on auth screen");
}
} else {
//Send to welcome screen
print('User is signed in!');
Navigator.pushReplacement(context, MaterialPageRoute(builder: (BuildContext context) => WelcomeScreen()));
}
});
非常感谢任何有关如何防止此错误的建议。
最佳答案
您必须像这样在有状态小部件的 dispose
方法中处理监听器:
class Sample extends StatefulWidget {
@override
_SampleState createState() => _SampleState();
}
class _SampleState extends State<Sample> {
StreamSubscription<User> _listener;
@override
Widget build(BuildContext context) {
return Container();
}
@override
void initState() {
_listener = FirebaseAuth.instance.authStateChanges().listen((User user) {
if (user == null) {
print('User is currently signed out!');
if (AuthScreen.id != '/AuthScreen') {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (BuildContext context) => AuthScreen()));
} else {
print("Already on auth screen");
}
} else {
//Send to welcome screen
print('User is signed in!');
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (BuildContext context) => WelcomeScreen()));
}
});
super.initState();
}
@override
void dispose() {
_listener.cancel();
super.dispose();
}
}
关于ios - Flutter + Firebase 抛出未处理的异常 : This widget has been unmounted Error Using Navigator to change view,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/66896767/