static CollectionReference doses =
      FirebaseFirestore.instance.collection('Doses');
  void setDoseDetails(
      TextEditingController endController,
      TextEditingController startController,
      TextEditingController doseController,
      int noPills,
      int doseRep) {
    var dose =
        doses.where('userID', isEqualTo: Auth().uID).get() as DocumentSnapshot;
    Map<String, dynamic> userData = dose as Map<String, dynamic>;
    endController.text = userData['endDate'];
    startController.text = userData['startDate'];
    noPills = userData['noPills'];
    doseController.text = userData['doseVal'];
    doseRep = userData["doseRep"];
  }

I'm trying to retrieve data from Firebase using this code and it's not working.

CodePudding user response：

If you see the return type of the get() method that you are trying to call in doses.where('userID', isEqualTo: Auth().uID).get() it is Future<QuerySnapshot<T>>. There are two problems in your approach:

1. You are not awaiting the for the result of doses.where('userID', isEqualTo: Auth().uID).get().

2. You are forcefully type-casting a QuerySnapshot into a DocumentSnapshot. If doses.where('userID', isEqualTo: Auth().uID).get() after awaiting, returns a QuerySnapshot, the variable holding that value should also be of the type QuerySnapshot.

Here is what you can do instead:

  static CollectionReference doses =
      FirebaseFirestore.instance.collection('Doses');
  Future<void> setDoseDetails(
      TextEditingController endController,
      TextEditingController startController,
      TextEditingController doseController,
      int noPills,
      int doseRep) async {
    QuerySnapshot dose =
        await doses.where('userID', isEqualTo: Auth().uID).get();
    Map<String, dynamic> userData = dose as Map<String, dynamic>;
    endController.text = userData['endDate'];
    startController.text = userData['startDate'];
    noPills = userData['noPills'];
    doseController.text = userData['doseVal'];
    doseRep = userData["doseRep"];
  }

If you notice in the solution above,

1. I have changed the return type of setDoseDetails because it can't be just void and has to be Future<void> because you are dealing with futures.

2. I have put an await keyword in front of the doses.where('userID', isEqualTo: Auth().uID).get(). This will allow for the response to return and then be assigned to the variable dose.

To read more about futures I would suggest going through https://api.flutter.dev/flutter/dart-async/Future-class.html.

Hope that helps!

CodePudding user response：

This might work for you:

var dose =
        await doses.where('userID', isEqualTo: Auth().uID).get();
    var userData = dose.docs.first.data();
    endController.text = userData['endDate'];
    startController.text = userData['startDate'];
    noPills = userData['noPills'];
    doseController.text = userData['doseVal'];
    doseRep = userData["doseRep"];