Flutter Firestore getDocuments() not working on initState

Question

I'm having an issue trying to call a document from Firestore in initState. I can pull data from a StreamBuilder just fine, but I just want to call the data once on initState.

Here is what I'm doing:

class _PainLevelState extends State<PainLevel> {
  final FirebaseAuth _auth = FirebaseAuth.instance;
  final CollectionReference userCollection =
      Firestore.instance.collection('users');
  static final now = DateTime.now();
  String _uid;
  double myPainLevel = 0;

  Future<void> getCurrentUser() async {
    final FirebaseUser user = await _auth.currentUser();
    if (mounted) {
      setState(() {
        _uid = user.uid;
      });
    }
  }

  Future<void> getCurrentPainLevel() async {
    await userCollection
        .document(_uid)
        .collection('pain')
        .where('time',
            isGreaterThanOrEqualTo: DateTime(now.year, now.month, now.day))
        .getDocuments()
        .then((QuerySnapshot docs) {
      if (docs.documents.isNotEmpty) {
        print('yes');
      } else {
        print('no'); 
      }
    });
  }

  @override
  void initState() {
    super.initState();
    getCurrentUser();
    getCurrentPainLevel();
  }

...

I just get a "no" every time I print to console. It's not get any documents when there is one. If I take the same code inside the future and put it somewhere else, like in the build method, it works, but it constantly builds and I don't want that. Any suggestion as to why it is not working? Thanks in advance.

Limbou Limbou · Accepted Answer · 2020-06-08T20:05:18

I'm guessing here that your code will not always work, because getCurrentPainLevel might get called before getCurrentUser is completed, which will cause _uid to be null and therefore, not work as expected. Try to put then keyword after getCurrentUser method, like this:

@override
  void initState() {
    super.initState();
    getCurrentUser().then((_) {
      getCurrentPainLevel();
    });
  }

By the way, you should NOT be calling async methods in initState. Try to put the code somewhere else, like WidgetsBinding.instance.addPostFrameCallback(...).

Flutter Firestore getDocuments() not working on initState

1 Answers