I am making a water Tracker application. I want to access the value of the recommended water quantity per day which I stored in a fire Store in a collection of users. And each user has a different value as it depends on his age and weight

class waterResults extends State<waterResultss> {
  bool isVisible= false;
  String d ="0";
TextEditingController addd = TextEditingController();
  double b = 0;
  int v=0;

  final Stream<QuerySnapshot> _usersStream =
  Widget build(BuildContext context) {

    return Material(
      child: ListView(
        padding: const EdgeInsets.all(20),
        children: <Widget>{

    stream: _usersStream,
    builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
      if (snapshot.hasError) {
        return const Text('Something went wrong');

      if (snapshot.connectionState == ConnectionState.waiting) {
        return const Text("Loading");

                  padding: const EdgeInsets.all(20),
                  child: CircularPercentIndicator(
                    lineWidth: 25.0,
                    radius:180 ,
                    animation: true,
                    backgroundColor: Colors.black,
                    percent: b/ v,
                    center: const Text(
                      "You can do it!",
                    progressColor: Colors.blue,
                    circularStrokeCap: CircularStrokeCap.round,

    ] ),);

  Future<Int> getResultUID(String uid) async {

    final snapshot = await FirebaseFirestore.instance
        .where('uid', isEqualTo: uid)
      v = snapshot.docs.first['results'];

    return snapshot.docs.first['results'];

Thanks in advance. Please help me I tried lots of past answers none of them worked