Dart/Flutter - “yield” inside a callback function

Question

I need to yield a list for a function; however, I want to yield the list from within a callback function, which itself is inside the main function - this results in the yiel

Answer 1

Instead of .listen which handles events inside another function you can use await for to handle events inside the outer function.

Separately - you might want to reconsider the pattern when you yield List instances that are still getting populated inside an inner stream callback...

Stream> fetchEvents() async* {
  final snapshots =
      Firestore.instance.collection('events').getDocuments().asStream();
  await for (final snapshot in snapshots) {
    // The `await .toList()` ensures the full list is ready
    // before yielding on the Stream
    final events = await snapshot.documents
        .map((document) => EventModel.fromJson(document.data))
        .toList();
    yield events;
  }
}