get data from one API that is dependent on another API flutter - flutter

Question

Hello friends I am learning to build apps in Flutter. it's a single screen must display data from second api using user_id value from the first api.I have api response from server like this :
{
"code": 0,
"message": "",
"data": [
{
"userbox_id": 7,
"user_id": 53,
"box_id": 55,
"status": 0,
"created_at": "2021-04-28T11:55:12.000000Z",
"updated_at": "2021-04-28T11:55:12.000000Z"
},
{
"userbox_id": 8,
"user_id": 53,
"box_id": 56,
"status": 0,
"created_at": "2021-04-29T10:29:43.000000Z",
"updated_at": "2021-04-29T10:29:43.000000Z"
},
"error": [],
"status": 200
}
I would like to use "user_id" value to fetch data from second API response .
How i can do that ?
the first method:
Future<List<ActiveBox>> fetchBoxes() async {
SharedPreferences localStorage = await SharedPreferences.getInstance();
String token = localStorage.getString('access_token');
await checkInternet();
Map<String, String> headers = {
'Content-type': 'application/json',
'Accept': 'application/json',
'Authorization': 'Bearer $token'
};
var url = Uri.parse(ApiUtil.GET_ALL_BOXES);
var response = await http.get(url, headers: headers);
switch (response.statusCode) {
case 200:
// print(response.statusCode);
var body = jsonDecode(response.body);
print(body);
List<ActiveBox> boxes = [];
for (var item in body['data']) {
boxes.add(ActiveBox.fromJson(item));
}
print(boxes);
inspect(boxes);
return boxes;
and the second method :
Future<User> getUser() async {
SharedPreferences localStorage = await SharedPreferences.getInstance();
String token = localStorage.getString('access_token');
print(token);
await checkInternet();
Map<String, String> headers = {
'Content-type': 'application/json',
'Accept': 'application/json',
'Authorization': 'Bearer $token'
};
var url = Uri.parse(ApiUtil.GET_USER);
var response = await http.get(url, headers: headers);
switch (response.statusCode) {
case 200:
var body = jsonDecode(response.body);
User users = User.fromJson(body);
return users;
how i can implement that ? any help please