The argument type 'CollectionReference<Object?>' can't be assigned to the parameter type 'Query<Map<String, dynamic>>'. (Documentation)

Question

I'm writing an app to show nearby ATMs. I want to pass the collection refernce and i get this error.

Stream nearbyATM() async* {
    GeoFirePoint point = geo.point(latitude: _position!.latitude, longitude: _position!.longitude);
    final CollectionReference atms = _firestore.collection("atms");
    double radius = 100;
    String field = "location";
    Stream<List<DocumentSnapshot>> stream = geo
                            .collection(collectionRef: atms)
                            .within(center: point, radius: radius, field: field);
  }

Answer 1

To use the .within() method with the GeoFlutterFire package, you need to pass a Query object as an argument to the GeoFireCollectionRef.collection() method.

You can directly use var query = _firestore.collection("atms").where(field, isLessThanOrEqualTo: point.distance, isGreaterThan: point.distance - radius); to make the inference do it’s thing but If we can also define the Types implicitly as follows:

Stream nearbyATM() async* {
  GeoFirePoint point = geo.point(latitude: _position!.latitude, longitude: _position!.longitude);
  double radius = 100;
  String field = "location";
// Let the Auto inference do it’s thing
  Query<Map<String, dynamic>> query =  _firestore.collection("atms").where(field, isLessThanOrEqualTo: point.distance, isGreaterThan: point.distance - radius);
// You can also 
  Stream<List<DocumentSnapshot>> stream = geo.collection(collectionRef: query).within(center: point, radius: radius, field: field);
}

We can pass Firebase Query to the collectionRef of geo.collection not just CollectionRef of firestore only.

Reference : geoflutterfire.