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use-ref-and-state-synchronously

v1.34.0
warning
effort: 6m
teams+

Warns when a notifier's ref or state are called past an await point (also known as asynchronous gap).

Using ref or state after an async gap will lead to UnmountedRefException if the notifier is already unmounted.

Try checking for ref.mounted before using ref or state.

Example​

❌ Bad:

@riverpod
class CountNotifier extends _$CountNotifier {
  @override
  int build() => 0;

  Future<void> incrementDelayed() async {
    await Future<void>.delayed(const Duration(seconds: 1));
    // LINT: Avoid accessing 'ref' or 'state' past an await point without checking if the ref is mounted.
    state += 1;
  }
}

class MyWidget extends StatelessWidget {
  const MyWidget({super.key});

  @override
  Widget build(BuildContext context) => GestureDetector(
    child: const Text('show dialog'),
    onTap: () => showDialog(
      context: context,
      builder: (context) => Consumer(
        builder: (context, ref, _) => AlertDialog(
          actions: [
            GestureDetector(
              child: const Text('increment and close'),
              onTap: () {
                ref.read(countProvider.notifier).incrementDelayed();
                Navigator.of(context).pop();
              },
            ),
          ],
        ),
      ),
    ),
  );
}

✅ Good:

@riverpod
class CountNotifier extends _$CountNotifier {
  @override
  int build() => 0;

  Future<void> incrementDelayed() async {
    await Future<void>.delayed(const Duration(seconds: 1));
    if (ref.mounted) {
      state += 1;
    }
  }
}

class MyWidget extends StatelessWidget {
  const MyWidget({super.key});

  @override
  Widget build(BuildContext context) => GestureDetector(
    child: const Text('show dialog'),
    onTap: () => showDialog(
      context: context,
      builder: (context) => Consumer(
        builder: (context, ref, _) => AlertDialog(
          actions: [
            GestureDetector(
              child: const Text('increment and close'),
              onTap: () {
                ref.read(countProvider.notifier).incrementDelayed();
                Navigator.of(context).pop();
              },
            ),
          ],
        ),
      ),
    ),
  );
}

Additional Resources​

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