asData?.value should be always mapped to null when loading

[23doors]

Describe the bug

provider.asData?.value is returning previous value even if isLoading is true.

To Reproduce

// declare some basic provider (reproduced with Family provider but I guess it should occur without Family as well)
@riverpod
Future<int?> someData(SomeDataRef ref, {required int something}) async {
    await Future.delayed(Duration(seconds: 10));
    return something;
}

...
// in build:

final data = ref.watch(someDataProvider(0));
print("${data.isLoading} ${data.asData?.isLoading} ${data.asData?.value != null}");

...
// invalidate provider somewhere else
ref.invalidate(someDataProvider(0));

Once value is there, after invalidate isLoading will be = true, but data.asData?.value will still be holding a value (it will not map it to null as expected). So before new value is loaded you get true true true as output (which in theory should never happen).

Even with .map you get:

    data.map(
      data: (v) {
        print("hasData and yet isLoading=${data.isLoading}");
        return null;
      },
      error: (v) {
        print("hasError");
        return null;
      },
      loading: (v) {
        print("isLoading");
        return null;
      },
    );

flutter: hasData and yet isLoading=true
flutter: hasData and yet isLoading=false

loading is never fired in this case.

Expected behavior

When isLoading = true, asData?.value should be null (which is how docs describe it as well).

[rrousselGit]

That's the expected behavior of AsyncData.
During a refresh, an AsyncData with isLoading=true is returned.

What you can do is asyncValue.unwrapPrevious().value

[23doors]

  /// If you do not want to return previous value during loading/error states,
  /// consider using [asData] :
  ///
  /// ```dart
  /// ref.watch(provider).asData()?.valueOrNull;
  /// ```

  /// Upcast [AsyncValue] into an [AsyncData], or return null if the [AsyncValue]
  /// is in loading/error state.

If that's expected behavior, then it is completely different from what docs describe it to be.

[rrousselGit]

Good call, I've fixed this on master.

[AhmedLSayed9]

@rrousselGit valueOrNull docs should be updated too

riverpod/packages/riverpod/lib/src/common.dart

Line 516 in 6031730

/// ref.watch(provider).asData()?.valueOrNull;