Issue with parsing Json data in flutter

May 27, 2023

I am trying to parse the below Json data:

{
    "userData": {
        "userId": 29922,
        "applicationId": 28,
        "siteId": 66
    },
    "verificationStatus": true
}

My Model Class:

import 'dart:convert';

class LoginResponse {
  final UserData userData;
  final bool verificationStatus;

  LoginResponse({required this.userData, required this.verificationStatus});

  factory LoginResponse.fromJson(Map<String, dynamic> json) {
    return LoginResponse(
        verificationStatus: json['verificationStatus'] as bool,
        userData: UserData.fromJson(json['userData']) ,
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['userData'] = this.userData;
    data['verificationStatus'] = this.verificationStatus;
    return data;
  }
}

class UserData{
  final String userId;

  UserData({required this.userId});

  factory UserData.fromJson(Map<String, dynamic> json) {
    return UserData(
      userId: json['userId'] as String
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['userId'] = this.userId;
    return data;
  }
}

main.dart

//loginResponse.body is the Json data
http.Response loginResponse = await postRequest();
LoginResponse response = jsonDecode(loginResponse.body);
print('status:>>$response.verificationStatus');
print('userId:>>$response.userData.userId');

But I am getting Unhandled Exception: type '_Map<String, dynamic>' is not a subtype of type 'LoginResponse'

>Solution :

You problem is here;

LoginResponse response = jsonDecode(loginResponse.body);

Should change like below;

Map<String, dynamic> parsedData = jsonDecode(loginResponse.body);
UserData userData = UserData.fromJson(parsedData);

And also, according to the provided JSON, the userId is not of type String; it is of type int. Therefore, you should change ‘String’ to ‘int’ in the UserData class.