A function prints the value but It's not printed on another function when returned

Question

I'm trying to get the near by location using firebase query and it goes well. This the function that gets the nearby location.

Future<List<DocumentSnapshot>> nearbyLocations() async {
    CollectionReference collectionRefer =
        FirebaseFirestore.instance.collection('locations');
    double radius = 10;
    String field = 'position';
    List<DocumentSnapshot> docList;
    GeoFirePoint center = await getCurrentLocation();
    // print(center);
    Stream<List<DocumentSnapshot>> stream = geo
        .collection(collectionRef: collectionRefer)
        .within(center: center, radius: radius, field: field, strictMode: true);
    stream.listen((List<DocumentSnapshot> documentList) {
      if (documentList.length > 0) {
        print(documentList[0].data());
        docList = documentList;
      } else {
        return {};
      }
    });
  }

I know that the query will return only one data. So, I printed on the first value in the above function. The problem arises when the documentList is returned.

loadData() async {
    documentList =
        await GeoLocator().nearbyLocations();
  }

When I call this above function, It prints null. But When I tried to print in the nearbyLocations() It print the data. But not when I Call loadData(). I'm going to use this returned data in listview.

Answer 1

You are mixing await, streams and then. This is probably too much to keep in mind at the same time.

Focus on one method at first. I suggest async/await since that is the easiest.

Your nearbyLocations method does not return anything. You did not define a type and it does not have a return statement either. Yet, you seem to expect it to return a Future<> with a specified type.

Make sure you crank up your warnings and use the pedantic package to have your analyzer notify you when you forget those things.

When you actually declare your method fully, your warnings should show you that you have no return in your method.

---

I don't have a compiler here or packages to include, but this seems to be what you really want:

Future<List<DocumentSnapshot>> nearbyLocations() async {
    final collectionRefer = FirebaseFirestore.instance.collection('locations');
    final radius = 10.0;
    final field = 'position';
    final center = await getCurrentLocation();

    final stream = geo
        .collection(collectionRef: collectionRefer)
        .within(center: center, radius: radius, field: field, strictMode: true);

    return stream.first;
  }