当我在我的手机号码错误时单击登录按钮然后打开一个错误对话框之后当我在对话框上单击确定时我得到了这个错误。
我收到这条消息
这个小部件已经被卸载，所以状态不再有上下文 （并且应该被认为是不存在的）
考虑在“处置”或使用 “mounted”吸气剂以确定状态是否仍然有效。
class _LoginPageState extends State<LoginPage> {
final GlobalKey<FormState> _formKey = GlobalKey();
TextEditingController _mobileController = new TextEditingController();
// TextEditingController _nameController = new TextEditingController();
// TextEditingController _emailController = new TextEditingController();
TextEditingController _passwordController = new TextEditingController();
Map<String, String> _authData = {
'user_name': '',
'user_email': '',
'username': '',
'password': ''
};
Future _submit() async {
print('aa' + _authData['username']);
if (!_formKey.currentState.validate()) {
return;
}
_formKey.currentState.save();
try {
await Provider.of<Auth>(context, listen: false).login(
_authData['user_name'],
_authData['user_email'],
_authData['username'],
_authData['password']);
print('authData_username' + _authData['username']);
print('authData_password' + _authData['password']);
} on HttpException catch (e) {
// } catch (e) {
var errorMessage = 'Authentication Failed';
if (e.toString().contains('Entered wrong mobile number!')) {
errorMessage = 'Entered wrong mobile number!';
print(errorMessage);
_showerrorDialog(errorMessage);
} else if (e.toString().contains('Entered wrong password!')) {
errorMessage = 'Entered wrong password!';
_showerrorDialog(errorMessage);
}
} catch (error) {
var errorMessage = 'Please try again later';
_showerrorDialog(errorMessage);
}
}
@override
void dispose() {
// TODO: implement dispose
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: ListView(
children: <Widget>[
Container(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height / 3.5,
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
colors: myGradient2),
borderRadius:
BorderRadius.only(bottomLeft: Radius.circular(90))),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Spacer(),
Align(
alignment: Alignment.center,
child: Icon(
Icons.person,
size: 90,
color: kWhite,
),
),
Spacer(),
Align(
alignment: Alignment.bottomRight,
child: Padding(
padding: const EdgeInsets.only(bottom: 32, right: 32),
child: Text(
'Login',
style: TextStyle(color: kWhite, fontSize: 18),
),
),
),
],
),
),
Container(
height: MediaQuery.of(context).size.height / 2,
width: MediaQuery.of(context).size.width,
padding: EdgeInsets.only(top: 62),
child: Form(
key: _formKey,
child: Column(
children: <Widget>[
Container(
width: MediaQuery.of(context).size.width / 1.2,
// height: 45,
child: TextFormField(
keyboardType: TextInputType.name,
autofocus: false,
decoration: InputDecoration(
hintText: 'Username.',
contentPadding:
EdgeInsets.fromLTRB(20.0, 15.0, 20.0, 15.0),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(32.0)),
),
validator: (input) =>
input.length > 10 || input.length < 10
? "Mobile Number should be valid"
: null,
controller: _mobileController,
onSaved: (value) {
_authData['username'] = value;
},
// maxLength: 10,
),
),
SizedBox(
height: 10,
),
Container(
width: MediaQuery.of(context).size.width / 1.2,
// height: 45,
child: TextFormField(
keyboardType: TextInputType.text,
autofocus: false,
obscureText: true,
decoration: InputDecoration(
hintText: 'Password',
contentPadding:
EdgeInsets.fromLTRB(20.0, 15.0, 20.0, 15.0),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(32.0)),
),
validator: (input) => input.length < 3
? "Password should be more than 3 characters"
: null,
controller: _passwordController,
onSaved: (value) {
_authData['password'] = value;
},
),
),
Align(
alignment: Alignment.centerRight,
child: Padding(
padding: const EdgeInsets.only(top: 16, right: 32),
child: Text(
'Forgot Password ?',
style: TextStyle(color: Colors.grey),
),
),
),
Spacer(),
InkWell(
onTap: () {
_submit();
},
child: Container(
height: 45,
width: MediaQuery.of(context).size.width / 1.2,
decoration: BoxDecoration(
gradient: LinearGradient(
colors: myGradient2,
),
borderRadius:
BorderRadius.all(Radius.circular(50))),
child: Center(
child: Text(
'Login'.toUpperCase(),
style: TextStyle(
color: Colors.white,
fontWeight: FontWeight.bold),
),
),
),
),
],
),
),
),
SizedBox(
height: 50,
),
InkWell(
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text("Dnon't have an account ?"),
Text(
"Sign Up",
style: TextStyle(color: kGreen),
),
],
),
onTap: () {
// Navigator.pushNamed(context, '/signup');
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SignupPage()),
);
},
),
],
),
),
);
}
void _showerrorDialog(String message) {
showDialog(
context: context,
builder: (ctx) => AlertDialog(
title: Text(
'An Error Occurs',
style: TextStyle(color: Colors.blue),
),
content: Text(message),
actions: <Widget>[
FlatButton(
child: Text('Okay'), onPressed: () => Navigator.of(mounted).pop())
],
),
);
}
}
尝试使用
Navigator.pop()Navigator.of(context, rootNavigator: true).pop()而不是
Navigator.of(mounted).pop())使用这个：
if (mounted) {
...
}
这是因为您没有处置或取消任何订阅或控制器。TRr 处置或取消订阅或控制器。
在您的 MaterialApp 小部件中添加一个 GlobalKey 以保持状态，然后使用
navigatorKey.currentState?.pop()navigatorKey.currentState?.pushNamed(routeName)pushReplacementNamed... final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
@override
Widget build(BuildContext context) {
return MaterialApp(
...
navigatorKey: navigatorKey,
);
}
更新： 现在已经安装在构建上下文中的属性
if (context.mounted) {
...
}