useStreamSignal

Creates a new StreamSignal and subscribes to it.

A StreamSignal wraps a standard Dart Stream, capturing emitted events, errors, and done notifications as reactive states (loading, data, error). The host widget is automatically rebuilt on every stream emission.

Parameters#

• value: A callback returning the Stream to subscribe to.
• options: An optional StreamSignalOptions to configure the stream signal.
• keys: A list of objects to watch. If any key changes, the hook unsubscribes from the old stream and subscribes to the new one.

Example#

import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';
import 'package:signals_hooks/signals_hooks.dart';

class ChatMessagesWidget extends HookWidget {
  final String channelId;
  const ChatMessagesWidget({required this.channelId, super.key});

  @override
  Widget build(BuildContext context) {
    // Subscribes to chat stream, automatically switching streams if channelId changes
    final streamSignal = useStreamSignal(
      () => listenToChannel(channelId),
      keys: [channelId],
    );

    return streamSignal.value.map(
      data: (message) => Text('New message: ${message.text}'),
      error: (err, stack) => Text('Stream error: $err'),
      loading: () => const Text('Connecting to channel...'),
    );
  }
}