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json - 类型'String'不是'index'错误的'int'类型的子类型

问题描述

尝试将用户登录到应用程序时，我遇到了这个问题。

登录详细信息被发送到服务器，并在必要的身份验证后将结果发送回用户（仅将用户名和生成的令牌发送回用户 - 仅需要此数据），但在运行 forEach 以插入数据时然后抛出错误类型 'String' is not a subtype of type 'int' of 'index'，无法查明造成此问题的确切行

如果有人可以请帮我解决这个问题。

登录.dart

class Login with ChangeNotifier{
  User user;
  String token;

  Login({this.user,this.token});

  Login.fromJson(Map<String, dynamic> json) {
    user = json['user'] != null ? new User.fromJson(json['user']) : null;
    token = json['token'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.user != null) {
      data['user'] = this.user.toJson();
      data['token'] = this.token;
    }
    return data;
  }
}

class User with ChangeNotifier{
  String createdAt;
  String sId;
  String userName;
  String password;
  int iV;
  

  User(
      {this.createdAt,
      this.sId,
      this.userName,
      this.password,
      this.iV,
      
      });

  User.fromJson(Map<String, dynamic> json) {
    createdAt = json['createdAt'];
    sId = json['_id'];
    userName = json['username'];
    password = json['password'];
    iV = json['__v'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['createdAt'] = this.createdAt;
    data['_id'] = this.sId;
    data['username'] = this.userName;
    data['password'] = this.password;
    data['__v'] = this.iV;
    return data;
  }
}

提供者.dart

class LoginProvider with ChangeNotifier {

 List<Login> _loginDetails = [];

List<Login> get items {
  return [..._loginDetails];
}

Future<void> addLoginDetails(User loginDetailscheck ) async {
print("reached");
Map<String, String> headers = {
"Content-Type": "charset=utf-8",    
"Content-type": "application/json"};

  const url = 'http://localhost:3000/login/cred';

 try
  {
  var response = await http.post(url, headers: headers,body:  
   json.encode({
    "user_name": loginDetailscheck.userName,
    "password": loginDetailscheck.password,
    "created_at": loginDetailscheck.createdAt,
    "_id":loginDetailscheck.sId
  })
  );
  final map  = json.decode(response.body) as Map<String,dynamic>;
  final List<Login> loadData = [];
  map.forEach((prodId, datacheck) {
    loadData.add( LoginPage(
      user: User(
        userName: datacheck['username'],
        ),
      token: json.decode(response.body)['token'],
    )
    );
    print(datacheck['username']);
    print(json.decode(response.body)['token']);
   });

  if(response.statusCode == 201) {
    _loginDetails = loadData;
  print(json.decode(response.body));
  notifyListeners();    
  }else{
    print('invalid data ');
  }
  }catch(error) {
    throw (error);
  }

}
}

收到的数据格式：

{
    "user": {
        "username": "Tom",
        "__v": 82
    },
    "token": "eyJhbGciOiJIUzICJ9.eyJfaWQiOiI1ZjA1NmY5YWI3NNDc1MDF9.zxii8_5DX9dSg-htXXbPfz0qKDI1"
}

ui.dart

class LoginHome extends StatefulWidget {
  @override
  _LoginHomeState createState() => _LoginHomeState();
}

class _LoginHomeState extends State<LoginHome> {


final _form = GlobalKey<FormState>();

var _dLogin = User(
    createdAt: DateTime.now().toString(),
    userName: '',
    password: '',


Future<void> _savedetails() async{
  final isValid = _form.currentState.validate();
  if(!isValid) {
     return;
  }

);
  _form.currentState.save();
  await Provider.of<LoginProvider>(context, listen: false).addLoginDetails(_dLogin) 
        .catchError((error) {
        Scaffold.of(context).showSnackBar(SnackBar(content: Text('Network error...'),));
  }
  );


@override
  Widget build(BuildContext context) {
    return  
         Column(
           mainAxisAlignment: MainAxisAlignment.center,
           crossAxisAlignment: CrossAxisAlignment.center,
            Container(
             child: SingleChildScrollView(
             child: Form(
               key:_form,
               child: Column(
                 mainAxisAlignment: MainAxisAlignment.center,
                 crossAxisAlignment: CrossAxisAlignment.center,
                 children: <Widget>[
                Container(
                  height: 70,
                  width: double.infinity,
                  margin:EdgeInsets.only(top: 40,left: 10,right: 10),
                     child: TextFormField(
                     textAlign: TextAlign.start,
                      style: TextStyle(color: Colors.white),    
                       decoration: InputDecoration(
                         errorStyle: TextStyle(height: 0,color:Colors.transparent),
                         contentPadding: new EdgeInsets.only(top: 25.0,left: 100),
                      border: InputBorder.none,
                      prefixIcon: Padding(
                        padding: EdgeInsets.symmetric(vertical:20),
                        child: Icon(
                          Icons.email,
                          color: Colors.white,
                        ), 
                      ),   
                       hintText: 'Username',
                       //labelText: 'E-mail',
                       hintStyle: TextStyle(color:Colors.grey[400],
                       fontWeight: FontWeight.normal,
                       ),
                       ),
                       onSaved: (value) => {
                         _dLogin = User(
                           userName: value,
                           password: _editLogin.password,
                           createdAt: _editLogin.createdAt,
                           sId: _editLogin.sId,
                         )
                       },
                      validator: (value) {
                      if (value.length == 0)
                      return "";                     
                      else
                      return null; 
                   },
                    ),
                ),
                Container(
                  decoration: myboxDecoration(),
                  height: 70,
                  width: double.infinity,
                  margin:EdgeInsets.only(top: 20,bottom: 10,left: 10,right: 10),
                     child: TextFormField(
                      textAlign: TextAlign.start,
                      
                      style: TextStyle(
                        color: Colors.white
                        ),   
                      decoration: InputDecoration(
                      errorStyle: TextStyle(height: 0,color:Colors.transparent),  
                      contentPadding: new EdgeInsets.only(top: 25.0),
                      border: InputBorder.none,
                      prefixIcon: Padding(
                        padding: EdgeInsets.symmetric(vertical:20),
                        child: Icon(
                          Icons.lock_outline,
                          color: Colors.white,
                        ), // icon is 48px widget.
                      ),
                      
                       hintText: 'Password',
                       hintStyle: TextStyle(color:Colors.grey[400],
                       fontWeight: FontWeight.normal,
                       
                       ),
                       
                       ),
                       onSaved: (value) => {
                         _dLogin = User(
                           userName: _editLogin.userName,
                           password: value,
                           createdAt: _editLogin.createdAt,
                           sId: _editLogin.sId,
                         )
                       },
                       validator: (value) {
                       if (value.length == 0)
                       return "";                     
                       else if (value.length <= 5)
                       return "";                     
                     else
                       return null; 
                   },
                   obscureText: true,
                    ),
                ),
                
                Container(
                        width: double.infinity,
                        height: 200
                        margin: EdgeInsets.only(left:20,right:20,top:50), 
                        child: FlatButton(
                          textColor: Colors.white,
                          child:    
                            Text('LOGIN',
                            style: TextStyle(
                            fontSize: 20.0, 
                            ),
                            ),
                          onPressed:  _saveNotification, 
                            ),
                      ),      
                 ],
                 
             )
    )
             ),
           ),
           ]
    );
  }
}

标签： jsonflutterdart

解决方案

从代码中，我看到您需要在 map['user'] 上迭代每个循环，而不仅仅是在 map 上，这将为您提供内部对象数据。我只是在写它，只是通过打印 foreach 循环中的值来检查。我没有在我的笔记本电脑上检查它，但很快就会检查它。

只需检查编辑我已经采取了一个示例，您的 foreach 循环有问题。

 String response = '''{
    "user": {
        "username": "Tom",
        "__v": 82
    },
    "token": "eyJhbGciOiJIUzICJ9.eyJfaWQiOiI1ZjA1NmY5YWI3NNDc1MDF9.zxii8_5DX9dSg-htXXbPfz0qKDI1"
}''';

  

  @override
  initState() {
    super.initState();

    Map item = json.decode(response);
    print(item['token']);
    item['user'].forEach((key, value) {
      print(key);
      print(value);
      
    });

  }

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