Flutter: How to store or hold the value of the button that user has been clicked?

Question

I did a quiz question with 4 buttons options.

and I display several questions on one page. Example of the quiz page

Now how to store or hold the values of each button that the user clicked before I pass the values for POST request API.

currently what I know to do is just hold the latest values that the user clicked.

Btw I'm new to coding and flutter. Hope you guys can help me.

Here's the code that I did

                List<dynamic> sent;

                                        CustomCheckBoxGroup(
                                          buttonValuesList: [
                                            [
                                              snapshot.data.result[index].id,
                                              snapshot.data.result[index]
                                                  .options[0].id
                                            ],
                                            [
                                              snapshot.data.result[index].id,
                                              snapshot.data.result[index]
                                                  .options[1].id
                                            ],
                                            [
                                              snapshot.data.result[index].id,
                                              snapshot.data.result[index]
                                                  .options[2].id
                                            ],
                                            [
                                              snapshot.data.result[index].id,
                                              snapshot.data.result[index]
                                                  .options[3].id
                                            ],
                                          ],
                                          buttonLables: [
                                            snapshot.data.result[index]
                                                .options[0].option,
                                            snapshot.data.result[index]
                                                .options[1].option,
                                            snapshot.data.result[index]
                                                .options[2].option,
                                            snapshot.data.result[index]
                                                .options[3].option,
                                          ],
                                          checkBoxButtonValues: (values) {
                                            sent=values;
                                            print(values);
                                          },
                                          selectedColor: Colors.orange,
                                          unSelectedColor: Colors.white70,
                                          horizontal: true,
                                        ),

and I want to send the value in array for the POST API

LIKE THIS

{
    "data":[{"question_id":1,"option_id":2},{"question_id":2,"option_id":6}]
}

While this is how I do for the post API

  Future<Sent> saveAnswer() async {
    setState(() {
      _isloading = true;
    });

    // var data = {"question_id": sent[0][0], "option_id": sent[0][1]};
    Map<String, List<Map<String, int>>> data = {
      "data": [
        {"question_id": sent[0][0], "option_id": sent[0][1]},
        {"question_id": sent[0][0], "option_id": sent[0][1]},
      ]
    };

    var url = await Network().link("/exercise/1/saveAnswer");
    SharedPreferences localStorage = await SharedPreferences.getInstance();
    final token = jsonDecode(localStorage.getString('token'));
    http.Response response =
        await http.post(Uri.parse(url), body: json.encode(data), headers: {
      'Content-type': 'application/json',
      'Accept': 'application/json',
      'Authorization': 'Bearer $token'
    });
    if (response.statusCode == 200) {
      print(response.body);
      print("Save success");
    } else {
      print(response.body);
      print("Save failed");
    }
  }

this is the response from the flutter if I click on the button

I/flutter ( 4884): [[1, 2]]

I/flutter ( 4884): [[2, 7]]

[question_id, option_id]

Answer 1

I think using RadioListTile for the multiple choices is better than manually using 4 buttons for each question. You can creatively make List variables to dynamically stores questions and answers.