How to cache data for a specific time on riverpod 2.6.1?

[lunxinfeng]

this is official advice:

extension CacheForExtension on AutoDisposeRef<Object?> {
  /// Keeps the provider alive for [duration].
  void cacheFor(Duration duration) {
    // Immediately prevent the state from getting destroyed.
    final link = keepAlive();
    // After duration has elapsed, we re-enable automatic disposal.
   Timer(duration, link.close);
  }
}


@riverpod
Future<Object> example(ExampleRef ref) async {
  ref.cacheFor(const Duration(minutes: 5));
  return http.get(Uri.https('example.com'));
}

but it will also cache when error, so do some change:

@riverpod
Future<Object> example(ExampleRef ref) async {
  var data = await http.get(Uri.https('example.com'));
  ref.cacheFor(const Duration(minutes: 5));
  return data;
}

but it cannot cache when only ref.read(no watch), so do some change like this:

extension CacheForExtension on AutoDisposeRef<Object?> {
  void cacheFor(Duration duration, {bool disposeOnError = true}) {
    final link = keepAlive();
    Timer(duration, link.close);

    if (disposeOnError) {
      listenSelf(
        (previous, next) {
          if (next is AsyncValue && next.hasError) {
            invalidateSelf();
          }
        },
        onError: (error, stackTrace) {
          invalidateSelf();
        },
      );
    }
  }
}

but when riverpod update to 2.6.1, ref.listenSelf is deprecated, here is no Notifier too.

How do I achieve the above functionality， cache data for a specified time, no cache when error, when only ref.read ?

Hope to answer, thks

[lunxinfeng]

also can do it like this:

  Future<T> cacheFor<T>(Duration duration, Future<T> Function() fun) async {
    final link = keepAlive();
    final timer = Timer(duration, link.close);
    try {
      return await fun.call();
    } catch (e) {
      timer.cancel();
      return Future.error(e);
    }
  }

But it doesn't look elegant at all.

[Trung15010802]

Have you checked the new docs:

[lunxinfeng]

Thks for answer.

Of course I know, but it not work fine like I said above:

1. cache data
2. not cache when error
3. only read(provider), no watch

I hope to achieve that as long as ref.read is called, no error is reported, it will be cached some time.

here is a demo, you can try it:

extension CacheForExtension on Ref<Object?> {
  /// Keeps the provider alive for [duration].
  void cacheFor(Duration duration) {
    final link = keepAlive();
    final timer = Timer(duration, link.close);
    // onDispose(timer.cancel);
  }
}

@riverpod
Future<int> randomInt(Ref ref) async {
  await Future.delayed(const Duration(seconds: 1));
  int num = Random().nextInt(100);
  ref.cacheFor(const Duration(seconds: 10));
  return num;
}

class RiverpodTest extends ConsumerWidget {
  const RiverpodTest({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Center(
      child: ElevatedButton(
          onPressed: () async {
            var num = await ref.read(randomIntProvider.future);
            print(num); // not cache
          },
          child: const Text("Random Num")),
    );
  }
}

[Trung15010802]

Oh I see, you should open an issue

[lunxinfeng]

#3817