Function returning null in FLutter

Question

I am trying to implement the function below but it gives me null.

To be specific, Future credit() is not updating the variable value. There is no problem with the database because if I put print(doc['value']) instead of value += doc['value'], I get the expected result. It seems, getCredit() is the one returning null.

Future credit() async {
    final FirebaseUser user = await FirebaseAuth.instance.currentUser();
    final String uid = user.uid;
    int value = 0;
    Firestore.instance
        .collection('entries')
        .where("uid", isEqualTo: uid)
        .where("type", isEqualTo: "+")
        .orderBy("time", descending: true)
        .snapshots()
        .listen((data) => data.documents.forEach((doc) => value += doc['value']));
    print(value); // doesnt update value
    return value;
  }

  int getCredit() {
    credit().then((value) {print(value);});
    credit().then((value) {return value;});  // return mot working
  }

Thanks!

M.B · Accepted Answer · 2020-05-20 13:21:00Z

2

try this:

Future<int> getCredit() async {
  return await  credit();
}

answered May 20, 2020 at 13:21

M.B

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parth shukla · Accepted Answer · 2020-05-20 22:58:37Z

0

Fixed it. It seems it was a problem with the scope of variable.

int cr = 0;
Future credit() async {
    final FirebaseUser user = await FirebaseAuth.instance.currentUser();
    final String uid = user.uid;
    Firestore.instance
        .collection('entries')
        .where("uid", isEqualTo: uid)
        .where("type", isEqualTo: "+")
        .orderBy("time", descending: true)
        .snapshots()
        .listen((data) => data.documents.forEach((doc) {cr = cr + doc['value'];}));

    print('$cr');
  }

answered May 20, 2020 at 22:58

parth shukla

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