颤振错误：此小部件已卸载，因此状态不再具有上下文（应视为已失效）
Posted
技术标签:
【中文标题】颤振错误：此小部件已卸载，因此状态不再具有上下文（应视为已失效）【英文标题】：flutter error: This widget has been unmounted, so the State no longer has a context (and should be considered defunct) 【发布时间】：2021-09-16 05:32:40 【问题描述】：当我点击登录按钮时我的手机号码错误然后打开一个错误对话框，然后当我点击对话框上的 okey 时出现此错误。
我收到了这条消息
此小部件已卸载，因此 State 不再具有上下文 （并且应该被认为是不复存在的）
考虑在“处置”或使用 "mounted" getter 以确定状态是否仍然处于活动状态。
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())
],
),
);
【问题讨论】：
【参考方案1】：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。
【讨论】：
【参考方案2】：此小部件已被卸载，因此 State 不再具有上下文（应视为已失效）。考虑取消任何。 答：
if (mounted)
...
【讨论】：
【参考方案3】：尝试使用
Navigator.pop() 或 Navigator.of(context, rootNavigator: true).pop()
而不是 Navigator.of(mounted).pop()) 来关闭 Dialog 窗口。
【讨论】：
以上是关于颤振错误：此小部件已卸载，因此状态不再具有上下文（应视为已失效）的主要内容，如果未能解决你的问题，请参考以下文章
错误：在此小部件上方找不到正确的提供程序 <List<Auftrag>>