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useStreamController

Creates a broadcast StreamController that lives across rebuilds and is closed automatically when the hook is disposed.

({void Function(String) onQueryChanged, String query}) useQueryStream() {
  // Broadcast controller, closed automatically when the hook is disposed.
  final controller = useStreamController<String>();

  // De-duplicate the raw input stream and expose the latest value.
  final latest = useStream(useMemoized(() => controller.stream.distinct()));

  return (
    // The View wires this to a text field; each call pushes onto the sink.
    onQueryChanged: controller.sink.add,
    query: latest.data ?? '',
  );
}

Signature​

StreamController<T> useStreamController<T>();

Returns a StreamController<T>.broadcast(). There are no parameters: the controller is created once, memoized for the lifetime of the hook, and close() is called on dispose.

Use cases​

  • Turning imperative callbacks into a Stream you can then transform - debounce a search field, throttle scroll events, merge several inputs.
  • Bridging a non-reactive API into the stream hooks (useStream, useStreamSubscription).

Caveats​

  • The controller is a broadcast controller, so it supports multiple listeners but does not buffer: events added before anyone listens are dropped, and a late listener sees only events from the moment it subscribes.

  • Do not call close() yourself - the hook owns the controller's lifecycle and closes it on dispose.

See also​