颤振问题文本窗口小部件，显示未显示错误
这是我创建的Flutter代码，由于某种原因，底部始终出现的错误文本不会出现。我创建了一个类似于此的登录页面，并且工作正常，但在该页面中，我使用的是onChanged而不是onSaved。我尝试使用它，但是一旦我在使用onChanged时开始键入键盘，键盘就会出现并消失，所以我使用了onSaved并消失了。
import 'package:flutter/material.dart';
import 'package:note_taker/authenticate/auth.dart';
import 'package:note_taker/shared/constants.dart';
class SignUp extends StatefulWidget {
final Function toggleView;
SignUp({@required this.toggleView});
@override
_SignUpState createState() => _SignUpState();
}
class _SignUpState extends State<SignUp> {
@override
Widget build(BuildContext context) {
final AuthService _auth = AuthService();
String _email;
String _password;
String error = '';
final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
Widget _buildHelloThere() {
return Container(
child: Column(
children: [
Container(
child: Stack(
children: [
Container(
// container for the HELLO TEXT
padding: EdgeInsets.only(
top: 80,
left: 20,
right: 0,
bottom: 0,
),
child: Text(
'HELLO',
style: TextStyle(
color: Colors.black,
fontSize: 60,
fontWeight: FontWeight.w900,
),
),
),
Container(
// container for the TEXT TEXT
padding: EdgeInsets.only(
top: 130,
left: 20,
right: 0,
bottom: 0,
),
child: Text(
'NEW',
style: TextStyle(
color: Colors.black,
fontSize: 60,
fontWeight: FontWeight.w900,
),
),
),
Container(
// container for the . TEXT
padding: EdgeInsets.only(
top: 130,
left: 160,
right: 0,
bottom: 0,
),
child: Text(
'USER',
style: TextStyle(
color: Colors.teal,
fontSize: 60,
fontWeight: FontWeight.w900,
),
),
),
],
),
),
],
),
);
}
Widget _buildEmail() {
return Container(
padding: EdgeInsets.symmetric(horizontal: 20),
child: TextFormField(
decoration: textDecorationForInput.copyWith(
labelText: 'Email',
labelStyle: TextStyle(color: Colors.teal),
),
validator: (value) {
Pattern pattern =
r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
RegExp regex = new RegExp(pattern);
if (value.isEmpty) {
return 'Email Required';
} else if (!regex.hasMatch(value)) {
return 'Enter Valid Email';
}
return null;
},
onSaved: (newValue) {
setState(() {
_email = newValue;
});
},
),
);
}
Widget _buildPassword() {
return Container(
padding: EdgeInsets.only(top: 30, left: 20, right: 20),
child: TextFormField(
decoration: textDecorationForInput.copyWith(
labelText: 'Password',
labelStyle: TextStyle(color: Colors.teal),
),
validator: (value) {
if (value.isEmpty) {
return 'Password Required';
} else if (value.length < 6) {
return 'Password too Small';
}
return null;
},
onSaved: (newValue) {
setState(() {
_password = newValue;
});
},
obscureText: true,
),
);
}
Widget _createSubmitButton() {
return Center(
child: RaisedButton(
color: Colors.teal,
padding: EdgeInsets.symmetric(horizontal: 130, vertical: 10),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(30),
),
child: Text(
'Sign In',
style: TextStyle(
color: Colors.white,
fontSize: 30,
fontWeight: FontWeight.bold,
),
),
onPressed: () async {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
dynamic result =
await _auth.signUpWithEmailAndPassword(_email, _password);
if (result == null) {
setState(() {
error = 'Problem with creating account';
});
}
}
},
),
);
}
Widget _createSignInButton() {
// to toggle between between sign up and log in
return FlatButton(
padding: EdgeInsets.only(left: 320),
onPressed: () {
//toggleView;
widget.toggleView();
},
child: Text(
'Sign up',
style: TextStyle(
color: Colors.blue,
fontSize: 20,
),
),
);
}
// this screen is next
return Scaffold(
resizeToAvoidBottomInset: true,
body: SingleChildScrollView(
child: Form(
key: _formKey,
child: Container(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
// build a text that says the word Hello
// build a text that says New
// build a tex that say User
_buildHelloThere(),
// create the text field for email
SizedBox(
height: 40,
),
_buildEmail(),
// create the text field for password
_buildPassword(),
//log in button
_createSignInButton(),
SizedBox(
height: 90,
),
// submit button
_createSubmitButton(),
// error print out
Center(
child: Text(
error,
style: TextStyle(
color: Colors.red,
fontSize: 20,
),
),
),
],
),
),
),
),
);
}
}
1 个答案:
答案 0 :(得分：0)
您可以在下面复制粘贴运行完整代码
步骤1：在variables中声明build，必须将它们移到build之外，以避免Sing-In失败并且setState将重置这些变量< br />
代码段
final AuthService _auth = AuthService();
String _email;
String _password;
String error = '';
final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
@override
Widget build(BuildContext context) {
第2步：您不需要setState中的onSaved
工作演示
完整代码
import 'package:flutter/material.dart';
class AuthService {
signUpWithEmailAndPassword(String email, String password) {
return null;
}
}
class SignUp extends StatefulWidget {
final Function toggleView;
SignUp({@required this.toggleView});
@override
_SignUpState createState() => _SignUpState();
}
class _SignUpState extends State<SignUp> {
final AuthService _auth = AuthService();
String _email;
String _password;
String error = '';
final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
@override
Widget build(BuildContext context) {
Widget _buildHelloThere() {
return Container(
child: Column(
children: [
Container(
child: Stack(
children: [
Container(
// container for the HELLO TEXT
padding: EdgeInsets.only(
top: 80,
left: 20,
right: 0,
bottom: 0,
),
child: Text(
'HELLO',
style: TextStyle(
color: Colors.black,
fontSize: 60,
fontWeight: FontWeight.w900,
),
),
),
Container(
// container for the TEXT TEXT
padding: EdgeInsets.only(
top: 130,
left: 20,
right: 0,
bottom: 0,
),
child: Text(
'NEW',
style: TextStyle(
color: Colors.black,
fontSize: 60,
fontWeight: FontWeight.w900,
),
),
),
Container(
// container for the . TEXT
padding: EdgeInsets.only(
top: 130,
left: 160,
right: 0,
bottom: 0,
),
child: Text(
'USER',
style: TextStyle(
color: Colors.teal,
fontSize: 60,
fontWeight: FontWeight.w900,
),
),
),
],
),
),
],
),
);
}
Widget _buildEmail() {
return Container(
padding: EdgeInsets.symmetric(horizontal: 20),
child: TextFormField(
decoration: InputDecoration(
labelText: 'Email',
labelStyle: TextStyle(color: Colors.teal),
),
validator: (value) {
Pattern pattern =
r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
RegExp regex = new RegExp(pattern);
if (value.isEmpty) {
return 'Email Required';
} else if (!regex.hasMatch(value)) {
return 'Enter Valid Email';
}
return null;
},
onSaved: (newValue) {
_email = newValue;
},
),
);
}
Widget _buildPassword() {
return Container(
padding: EdgeInsets.only(top: 30, left: 20, right: 20),
child: TextFormField(
decoration: InputDecoration(
labelText: 'Password',
labelStyle: TextStyle(color: Colors.teal),
),
validator: (value) {
if (value.isEmpty) {
return 'Password Required';
} else if (value.length < 6) {
return 'Password too Small';
}
return null;
},
onSaved: (newValue) {
_password = newValue;
},
obscureText: true,
),
);
}
Widget _createSubmitButton() {
return Center(
child: RaisedButton(
color: Colors.teal,
padding: EdgeInsets.symmetric(horizontal: 130, vertical: 10),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(30),
),
child: Text(
'Sign In',
style: TextStyle(
color: Colors.white,
fontSize: 30,
fontWeight: FontWeight.bold,
),
),
onPressed: () async {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
dynamic result =
await _auth.signUpWithEmailAndPassword(_email, _password);
if (result == null) {
setState(() {
error = 'Problem with creating account';
});
}
}
},
),
);
}
Widget _createSignInButton() {
// to toggle between between sign up and log in
return FlatButton(
padding: EdgeInsets.only(left: 320),
onPressed: () {
//toggleView;
widget.toggleView();
},
child: Text(
'Sign up',
style: TextStyle(
color: Colors.blue,
fontSize: 20,
),
),
);
}
// this screen is next
return Scaffold(
resizeToAvoidBottomInset: true,
body: SingleChildScrollView(
child: Form(
key: _formKey,
child: Container(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
// build a text that says the word Hello
// build a text that says New
// build a tex that say User
_buildHelloThere(),
// create the text field for email
SizedBox(
height: 40,
),
_buildEmail(),
// create the text field for password
_buildPassword(),
//log in button
_createSignInButton(),
SizedBox(
height: 90,
),
// submit button
_createSubmitButton(),
// error print out
Center(
child: Text(
error,
style: TextStyle(
color: Colors.red,
fontSize: 20,
),
),
),
],
),
),
),
),
);
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: SignUp(),
);
}
}
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