Relational Data Fetching
The pattern below is useful for listening to a realtime stream that depends on the current user’s UID. The switchmap extension method from RxDart is an essential tool for combining two streams.
firestore.dart
class FirestoreService {
/// Listens to current user's report document in Firestore
Stream<Report> streamReport() {
return AuthService().userStream.switchMap((user) {
if (user != null) {
var ref = _db.collection('reports').doc(user.uid);
return ref.snapshots().map((doc) => Report.fromJson(doc.data()!));
} else {
return Stream.fromIterable([Report()]);
}
});
}
}