Appbar should show number of records using futurebuilder in flutter

Question

I have just created a demo for better understanding future builder

scaffold body showing all users from api and appear should be shown with number of users

appear's title showing 0 when loaded but does not change...what to do to rebuild it

here is my code

class _withmodelState extends State<withmodel> {

  List<UserModel> userlist=[];

  Future<List<UserModel>> getdata() async {
    final resp =
        await http.get(Uri.parse('https://jsonplaceholder.typicode.com/users'));

    if (resp.statusCode == 200) {
      print('i ma called');
      List<dynamic> dlist = json.decode(resp.body);
      await Future.delayed(Duration(seconds: 2));

      userlist= dlist.map((e) => UserModel.fromJson(e)).toList();
      return userlist;
    }
    return userlist;


  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
        child: Scaffold(
          appBar: AppBar(title: Text("Total users="+userlist.length.toString()),),
      body: MyBody(
        //MyBody returning FutureBuilder for showing userlist array;
      ),
    ));
  }

Answer 1

You can use ChangeNotifier like this, first create a class like this:

class WithmodelDecl with ChangeNotifier {
  ValueNotifier<int> totalUsers = ValueNotifier<int>(0);
}

WithmodelDecl withmodeldecl = new WithmodelDecl();

then use it like this:

return SafeArea(
        child: Scaffold(
          appBar: PreferredSize(
          child: ValueListenableBuilder<int>(
              valueListenable: withmodeldecl.totalUsers,
              builder: (context, value, _) {
                return AppBar(
                  title: Text("Total users=" + value.toString()),
                );
              }),
          preferredSize: AppBar().preferredSize),
      body: MyBody(
        //MyBody returning FutureBuilder for showing userlist array;
      ),
));

and finally change your getdata to this:

Future<List<UserModel>> getdata() async {
    final resp =
        await http.get(Uri.parse('https://jsonplaceholder.typicode.com/users'));

    if (resp.statusCode == 200) {
      print('i ma called');
      List<dynamic> dlist = json.decode(resp.body);
      await Future.delayed(Duration(seconds: 2));

      userlist= dlist.map((e) => UserModel.fromJson(e)).toList();
      withmodeldecl.totalUsers.value = userlist.length;
      return userlist;
    }
    return userlist;


  }