问题：
未处理的异常：类型“List”不是类型“String”的子类型
宗政卓
我正在开发我的flutter应用程序的身份验证。请帮我解决这个问题。我无法识别返回这样一个错误的问题，声明未处理异常：类型列表不是类型字符串的子类型。
以下是登录屏幕的代码：
import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
class WelcomeBackPage extends StatefulWidget {
@override
WelcomeBackPageState createState() => WelcomeBackPageState();
}
class WelcomeBackPageState extends State<WelcomeBackPage> {
final _scaffoldKey = GlobalKey<ScaffoldState>();
final _formKey = GlobalKey<FormState>();
bool _isSubmitting, _obscureText = true;
String _email, _password;
Widget _showHello() {
return Text(
'Hello',
style: GoogleFonts.montserrat(
fontSize: 70.0,
fontWeight: FontWeight.w800,
textStyle: TextStyle(color: Colors.black)),
);
}
Widget _showThere() {
return Container(
padding: EdgeInsets.only(left: 5.0),
child: Text(
'There',
style: GoogleFonts.montserrat(
fontSize: 70.0,
fontWeight: FontWeight.w800,
height: 0.7,
textStyle: TextStyle(color: Colors.black)),
));
}
Widget _showDot() {
return Text(
'.',
style: GoogleFonts.montserrat(
fontSize: 70.0,
fontWeight: FontWeight.bold,
height: 0.7,
textStyle: TextStyle(color: Colors.green)),
);
}
Widget _showEmailInput() {
return Padding(
padding: EdgeInsets.only(top: 30.0, left: 5.0),
child: TextFormField(
onSaved: (val) => _email = val,
decoration: InputDecoration(
labelText: 'EMAIL',
labelStyle: TextStyle(
fontFamily: 'Montserrat',
fontWeight: FontWeight.bold,
color: Colors.grey),
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.grey[300]),
),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.green)),
),
keyboardType: TextInputType.emailAddress,
validator: (val) => !val.contains('@') ? 'Invalid Email' : null,
));
}
Widget _showPasswordInput() {
return Padding(
padding: EdgeInsets.only(top: 10.0, left: 5.0),
child: TextFormField(
onSaved: (val) => _password = val,
decoration: InputDecoration(
suffixIcon: GestureDetector(
onTap: () {
setState(() => _obscureText = !_obscureText);
},
child: Icon(
_obscureText ? Icons.visibility : Icons.visibility_off)),
labelText: 'PASSWORD',
labelStyle: TextStyle(
fontFamily: 'Montserrat',
fontWeight: FontWeight.bold,
color: Colors.grey),
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.grey[300]),
),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.green)),
),
obscureText: _obscureText,
validator: (val) => val.length < 6 ? 'Invalid Password' : null,
));
}
Widget _showForgotPassword() {
return Container(
alignment: Alignment(1.2, 0.0),
child: Padding(
padding: EdgeInsets.only(top: 0.0),
child: Column(
children: <Widget>[
FlatButton(
onPressed: () {},
child: Text(
'Forgot Password',
style: GoogleFonts.montserrat(
color: Colors.green,
fontSize: 16.0,
fontWeight: FontWeight.bold,
decoration: TextDecoration.underline),
),
),
],
),
));
}
Widget _showLogin() {
return Padding(
padding: EdgeInsets.only(top: 20.0),
child: ButtonTheme(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(100)),
child: Center(
child: _isSubmitting == true
? CircularProgressIndicator(
valueColor: AlwaysStoppedAnimation(Colors.green),
)
: RaisedButton(
onPressed: _login,
textColor: Colors.white,
color: Colors.green,
padding: EdgeInsets.all(5.0),
child: Container(
height: 50,
width: MediaQuery.of(context).size.width,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(100),
color: Colors.green),
padding: const EdgeInsets.all(15.0),
child: Text(
'LOGIN',
textAlign: TextAlign.center,
style: GoogleFonts.montserrat(
letterSpacing: 2.0,
fontSize: 18.0,
fontWeight: FontWeight.w600,
),
),
),
))));
}
void _login() {
final form = _formKey.currentState;
if (form.validate()) {
form.save();
_registerUser();
}
}
void _registerUser() async {
setState(() => _isSubmitting = true);
http.Response response = await http.post(
'http://192.168.43.9:1337/auth/local',
body: {"identifier": _email, "password": _password});
final responseData = json.decode(response.body);
if (response.statusCode == 200) {
setState(() => _isSubmitting = false);
_showSuccessSnack();
_redirectUser();
print(responseData);
} else {
setState(() => _isSubmitting = false);
final String errorMsg = responseData['message'];
_showErrorSnack(errorMsg);
}
}
void _showSuccessSnack() {
final snackbar = SnackBar(
content: Text(' User successfully logged in ',
style:
GoogleFonts.montserrat(color: Colors.green, fontSize: 16.0)));
_scaffoldKey.currentState.showSnackBar(snackbar);
_formKey.currentState.reset();
}
void _showErrorSnack(String errorMsg) {
final snackbar = SnackBar(
content: Text(errorMsg,
style: GoogleFonts.montserrat(color: Colors.red, fontSize: 16.0)));
_scaffoldKey.currentState.showSnackBar(snackbar);
throw Exception('Error logging in: $errorMsg');
}
void _redirectUser() {
Future.delayed(Duration(seconds: 2), () {
Navigator.pushReplacementNamed(context, '/intro');
});
}
Widget _showGoogle() {
return Padding(
padding: EdgeInsets.only(top: 20.0),
child: OutlineButton(
shape: StadiumBorder(),
textColor: Colors.black,
borderSide: BorderSide(
color: Colors.black, style: BorderStyle.solid, width: 2.5),
onPressed: () {},
padding: EdgeInsets.all(5.0),
child: Container(
height: 50,
width: MediaQuery.of(context).size.width,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Center(
child: ImageIcon(AssetImage('assets/facebook.png')),
),
SizedBox(width: 10.0),
Center(
child: Text(
'Log in with Google',
textAlign: TextAlign.center,
style: GoogleFonts.montserrat(
fontSize: 18.0,
fontWeight: FontWeight.w600,
),
),
)
],
),
),
));
}
Widget _showNewRegister() {
return Padding(
padding: EdgeInsets.only(top: 35.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'New to Oristore ?',
style: GoogleFonts.montserrat(
fontSize: 16.0,
fontWeight: FontWeight.w600,
),
),
SizedBox(width: 5.0),
InkWell(
onTap: () => Navigator.pushReplacementNamed(context, '/register'),
child: Text(
'Register',
style: GoogleFonts.montserrat(
fontSize: 17.0,
color: Colors.green,
fontWeight: FontWeight.w600,
decoration: TextDecoration.underline,
),
),
)
],
));
}
@override
Widget build(BuildContext context) {
return Scaffold(
key: _scaffoldKey,
resizeToAvoidBottomPadding: false,
resizeToAvoidBottomInset: true,
body: SingleChildScrollView(
child: Form(
key: _formKey,
child: Stack(children: <Widget>[
Container(
padding: EdgeInsets.symmetric(horizontal: 20.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
SizedBox(
height: 60.0,
),
Padding(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
_showHello(),
new Row(children: <Widget>[
_showThere(),
_showDot(),
]),
_showEmailInput(),
_showPasswordInput(),
_showForgotPassword(),
_showLogin(),
_showGoogle(),
_showNewRegister()
],
))
])),
//_showOTPAction(),
]))));
}
}
执行登录的上述代码部分：
void _login() {
final form = _formKey.currentState;
if (form.validate()) {
form.save();
_registerUser();
}
}
void _registerUser() async {
setState(() => _isSubmitting = true);
http.Response response = await http.post(
'http://192.168.43.9:1337/auth/local',
body: {"identifier": _email, "password": _password});
final responseData = json.decode(response.body);
if (response.statusCode == 200) {
setState(() => _isSubmitting = false);
_showSuccessSnack();
_redirectUser();
print(responseData);
} else {
setState(() => _isSubmitting = false);
final String errorMsg = responseData['message'];
_showErrorSnack(errorMsg);
}
}
void _showSuccessSnack() {
final snackbar = SnackBar(
content: Text(' User successfully logged in ',
style:
GoogleFonts.montserrat(color: Colors.green, fontSize: 16.0)));
_scaffoldKey.currentState.showSnackBar(snackbar);
_formKey.currentState.reset();
}
void _showErrorSnack(String errorMsg) {
final snackbar = SnackBar(
content: Text(errorMsg,
style: GoogleFonts.montserrat(color: Colors.red, fontSize: 16.0)));
_scaffoldKey.currentState.showSnackBar(snackbar);
throw Exception('Error logging in: $errorMsg');
}
void _redirectUser() {
Future.delayed(Duration(seconds: 2), () {
Navigator.pushReplacementNamed(context, '/intro');
});
}
错误
E/flutter ( 4862): [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'String'
E/flutter ( 4862): #0 WelcomeBackPageState._registerUser (package:oristore/screens/auth/welcome_back_page.dart:182:20)
E/flutter ( 4862): <asynchronous suspension>
E/flutter ( 4862): #1 WelcomeBackPageState._login (package:oristore/screens/auth/welcome_back_page.dart:165:7)
E/flutter ( 4862): #2 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:992:19)
E/flutter ( 4862): #3 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:1098:38)
E/flutter ( 4862): #4 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:184:24)
E/flutter ( 4862): #5 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:524:11)
E/flutter ( 4862): #6 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:284:5)
E/flutter ( 4862): #7 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:219:7)
E/flutter ( 4862): #8 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:477:9)
E/flutter ( 4862): #9 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:78:12)
E/flutter ( 4862): #10 PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:124:9)
E/flutter ( 4862): #11 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 4862): #12 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:122:18)
E/flutter ( 4862): #13 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:108:7)
E/flutter ( 4862): #14 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:220:19)
E/flutter ( 4862): #15 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
E/flutter ( 4862): #16 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:158:7)
E/flutter ( 4862): #17 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:104:7)
E/flutter ( 4862): #18 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:88:7)
E/flutter ( 4862): #19 _rootRunUnary (dart:async/zone.dart:1206:13)
E/flutter ( 4862): #20 _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 4862): #21 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter ( 4862): #22 _invoke1 (dart:ui/hooks.dart:267:10)
E/flutter ( 4862): #23 _dispatchPointerDataPacket (dart:ui/hooks.dart:176:5)
E/flutter ( 4862):
共有2个答案
昝唯
别峻
尝试使用此val？。长度使val为空。
类似资料：
-
我对使用颤振和特定于平台的代码非常陌生，所以如果这是一个愚蠢的问题，请原谅我。我正在使用一个事件通道将数据从android端返回到Flatter。我正在返回一份清单 但是，当我试图添加它时，它给出了一个异常，“未处理的异常：类型'列表'不是类型'列表'的子类型 这是我要将贴图对象添加到的列表。 列表 这是我的添加代码。忽略print语句。 我尝试过像cast或from这样的方法，但它对我不起作用，
-
更新：感谢@Rjulcaa回答我的地图现在是一个列表，但是列表没有显示在用户界面上。我转过来，我需要用FutureBuilder来处理未来，所以如果有人面临这个问题，记得在你的用户界面主体中添加一个FutureBuilder，并在构建器上返回你想要显示的小部件。 我正在制作一个todo列表教程，我正在尝试添加JSON上的编码功能，我的todoList将其保存在SharedReferences上，当
-
上面的代码给出了警告未处理的异常：类型'double'不是类型'string'的子类型
-
我试图解析json，将其打印到控制台，然后放入ListView.builder并得到这个错误：键入'_InternalLinkedHashMap 我要怎么修？ 列表数据 API服务 模型 非常感谢您的回答..................................................................................................
-
Family_View.Dart family_provider.dart
-
我正在解码一个响应体，我得到了错误： 我在Udemy上学习颤振教程时，正在尝试使用API。教程说要使用https://javiercbk.github.io/json_to_dart/将JSON转换为Dart。我把JSON从https://www.openbrewerydb.org/并将其转换为Dart，但我遇到的问题是，当我尝试解码API时，我得到了未处理的错误异常：“List”类型不是“Map