I am trying to fetch quizzes data from realtime database using http mathod "GET". The data is being retreived but it's not showing up in listview and when i print the length of my list it's 0. And this is what the error is being shown in my terminal: Error: Expected a value of type 'int', but got one of type 'String'

I can't figure out what the problem is. Please help me solve this problem because i am trying for around 5 days but can't solve it.

Thank you.

These are my codes for fetching the data in lists.

Future<void> getList() async {
    list.clear();
    final url = Uri.parse(
        'https://testisnotesttheisthelearningapp-default-rtdb.firebaseio.com/Schools/${widget.uid}/ResultsFolder/${widget.id}.json');
    final response = await get(url);
    print(response.body);
    var map = json.decode(response.body) as Map<String, dynamic>;
    // print(map);
    if (map != null) {
      map.forEach((key, value) {
        print(value['Name']);
        var temp = Result(
            value['Percent'],
            (value['choice'] as List<dynamic>)
                .map((e) => Model(e['index'], e['question'], []))
                .toList(),
            value['Score'],
            (value['question'] as List<dynamic>).map((e) => e).toList(),
            value['Name']);
        list.add(temp);
      });
    }
  }

This is my data from real-time database in JSON format:

{
  "Name" : "Miets Digital",
  "Percent" : 100,
  "Score" : 2,
  "choice" : [ "Correct", "Correct" ],
  "question" : [ {
    "question" : "WHo is Elon Musk?"
  }, {
    "question" : "How did Elon musk got rich?"
  } ]
}

CodePudding user response：

Try this:-

Future<void> getList() async {
    list.clear();
    final url = Uri.parse(
        'https://testisnotesttheisthelearningapp-default-rtdb.firebaseio.com/Schools/${widget.uid}/ResultsFolder/${widget.id}.json');
    final response = await get(url);
    print(response.body);
    var map = json.decode(response.body) as Map<String, dynamic>;
    // print(map);
    if (map != null) {
     print(map['Name']);
        var temp = Result(
            map['Percent'],
            (map['choice'] as List<dynamic>)
                .map((e) => Model(e['index'], e['question'], []))
                .toList(),
            map['Score'],
            (map['question'] as List<dynamic>).map((e) => e).toList(),
            map['Name']);
        list.add(temp);
    }
  }

forEach() loop goes through each key value pair in a map. The variables key and value gives you the key and the value the loop is currently working on. If you want to access the values of a map you will have to use the syntax map['key_name'].

This also explains the error, as your Result() constructor is expecting an integer but is getting a string value.

CodePudding user response：

It's not a good practice to parse JSON maps. You just call over the model class

Try to follow the below code

Future<QuizModelResponse> getList() async {
 // here write your code 
 var map = json.decode(response.body);
 return QuizModelResponse.fromJsonMap(map);
}

List Response class

class QuizModelResponse {
  List<QuizItemModel> content;

  QuizModelResponse.fromJsonMap(dynamic data) :
        content = List<QuizItemModel>.from(
            data.map((it) => QuizItemModel.fromJson(it)));
}

Model class

class QuizItemModel {
  String name;
  int percent;
  int score;
  List<String> choice;
  List<Question> question;

  QuizItemModel(
      {this.name, this.percent, this.score, this.choice, this.question});

  QuizItemModel.fromJson(Map<String, dynamic> json) {
    name = json['Name'];
    percent = json['Percent'];
    score = json['Score'];
    choice = json['choice'].cast<String>();
    if (json['question'] != null) {
      question = new List<Question>();
      json['question'].forEach((v) {
        question.add(new Question.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['Name'] = this.name;
    data['Percent'] = this.percent;
    data['Score'] = this.score;
    data['choice'] = this.choice;
    if (this.question != null) {
      data['question'] = this.question.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class Question {
  String question;

  Question({this.question});

  Question.fromJson(Map<String, dynamic> json) {
    question = json['question'];
  }

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