Flutter Riverpod : return 2 stream with StreamProvider - flutter

Question

I have music player application using package Asset Audio Player and Flutter Riverpod as State Management. I want listen 2 things stream :
Listen current duration of song
Listen current song played
final currentSongPosition = StreamProvider.autoDispose<Map<String, dynamic>>((ref) async* {
final AssetsAudioPlayer player = ref.watch(globalAudioPlayers).state;
ref.onDispose(() => player.dispose());
final Stream<double> _first = player.currentPosition.map((event) => event.inSeconds.toDouble());
final Stream<double> _second =
player.current.map((event) => event?.audio.duration.inSeconds.toDouble() ?? 0.0);
final maps = {};
maps['currentDuration'] = _first;
maps['maxDurationSong'] = _second;
return maps; << Error The return type 'Map<dynamic, dynamic>' isn't a 'Stream<Map<String, dynamic>>', as required by the closure's context.
});
How can i return 2 stream into 1 StreamProvider then i can simply using like this :
Consumer(
builder: (_, watch, __) {
final _currentSong = watch(currentSongPosition);
return _currentSong.when(
data: (value) {
final _currentDuration = value['currentDuration'] as double;
final _maxDuration = value['maxDuration'] as double;
return Text('Current : $_currentDuration, Max :$_maxDuration');
},
loading: () => Center(child: CircularProgressIndicator()),
error: (error, stackTrace) => Text('Error When Playing Song'),
);
},
),

Answer 1

I would start by creating a StreamProvider for each Stream:
final currentDuration = StreamProvider.autoDispose<double>((ref) {
final player = ref.watch(globalAudioPlayers).state;
return player.currentPosition.map((event) => event.inSeconds.toDouble());
});
final maxDuration = StreamProvider.autoDispose<double>((ref) {
final player = ref.watch(globalAudioPlayers).state;
return player.current.map((event) => event?.audio.duration.inSeconds.toDouble() ?? 0.0);
});
Next, create a FutureProvider to read the last value of each Stream.
final durationInfo = FutureProvider.autoDispose<Map<String, double>>((ref) async {
final current = await ref.watch(currentDuration.last);
final max = await ref.watch(maxDuration.last);
return {
'currentDuration': current,
'maxDurationSong': max,
};
});
Finally, create a StreamProvider that converts durationInfo into a Stream.
final currentSongPosition = StreamProvider.autoDispose<Map<String, double>>((ref) {
final info = ref.watch(durationInfo.future);
return info.asStream();
});

Answer 2

This answer is another approach what #AlexHartford do.
Current solution for my case is using package rxdart CombineLatestStream.list(), this code should be look then :
StreamProvider
final currentSongPosition = StreamProvider.autoDispose((ref) {
final AssetsAudioPlayer player = ref.watch(globalAudioPlayers).state;
final Stream<double> _first = player.currentPosition.map((event) => event.inSeconds.toDouble());
final Stream<double> _second =
player.current.map((event) => event?.audio.duration.inSeconds.toDouble() ?? 0.0);
final tempList = [_first, _second];
return CombineLatestStream.list(tempList);
});
How to use it :
Consumer(
builder: (_, watch, __) {
final players = watch(globalAudioPlayers).state;
final _currentSong = watch(currentSongPosition);
return _currentSong.when(
data: (value) {
final _currentDuration = value[0];
final _maxDuration = value[1];
return Slider.adaptive(
value: _currentDuration,
max: _maxDuration,
onChanged: (value) async {
final newDuration = Duration(seconds: value.toInt());
await players.seek(newDuration);
context.read(currentSongProvider).setDuration(newDuration);
},
);
},
loading: () => const Center(child: CircularProgressIndicator()),
error: (error, stackTrace) => Text(error.toString()),
);
},
),
But this approach have drawback, the code is hard to readable. Especially when use in Consumer, I have to know the order of return result.