StreamShard

StreamShard

StreamShard<T> manages state from a Stream. Perfect for real-time data like WebSocket connections, database listeners, or timers.

See Async Values for the AsyncValue<T> sealed class and Widgets for AsyncShardBuilder.

Creating a StreamShard

class MessagesStream extends StreamShard<List<Message>> {
  final String chatId;
  final ChatRepository repository;

  MessagesStream({required this.chatId, required this.repository});

  @override
  Stream<List<Message>> build() {
    return repository.watchMessages(chatId);
  }
}

Refreshing Stream

Call refresh() to cancel current subscription and re-subscribe:

// Reset the stream
context.read<TimerShard>().refresh();

Pausing & resuming

Use pause() and resume() to temporarily stop processing stream events without cancelling the subscription:

final messages = context.read<MessagesStream>();

messages.pause();      // pause the underlying subscription
messages.isPaused;     // true
messages.resume();     // deliver buffered events and continue

While paused, source events are buffered per Dart's StreamSubscription.pause semantics and delivered on resume. It's a no-op if the shard hasn't subscribed yet (for example, before onInit). Use it to stop processing while a screen is backgrounded.

Next Steps

Next: Persistent Shard to persist state across app sessions. See also: Examples.