Add default value for field on copyWith

[markokarajlovic]

I am using freezed for state class in bloc.

part 'example_state.freezed.dart';

@freezed
class ExampleState with _$ExampleState {
  const ExampleState._();

  const factory ExampleState({
    @Default(ExampleStateBuildStatus.loading) ExampleStateBuildStatus buildStatus,
    ExampleStateListenStatus? listenStatus,
  }) = _ExampleState;
}

enum ExampleStateBuildStatus {
  loading,
  loadSuccess,
}

enum ExampleStateListenStatus {
  error,
}

And every time I emit new state I need to pass null for listenStatus so listener on UI dont trigger every time or I need to override listenWhen to handle it.

emit(state.copyWith(listenStatus: null))

Can you implemented something like this so when I dont pass nothing it will get CopyWithDefault value:

part 'example_state.freezed.dart';

@freezed
class ExampleState with _$ExampleState {
  const ExampleState._();

  const factory ExampleState({
    @Default(ExampleStateBuildStatus.loading) ExampleStateBuildStatus buildStatus,
    @CopyWithDefault(null) ExampleStateListenStatus? listenStatus,
  }) = _ExampleState;
}

enum ExampleStateBuildStatus {
  loading,
  loadSuccess,
}

enum ExampleStateListenStatus {
  error,
}

[TetrixGauss]

Hello guys! This is an amazing feature to include with the package! Do you know if and when are we going to have it?

[rrousselGit]

I don't really have a plan to do that for now.

[shivamkj]

Currently have to manually write copyWithX even with freezed because of lack of this feature. Default value is often needed in CopyWith when working with bloc.

[phyueimon162]

This is also necessary for my project with Bloc. Please kindly consider adding this feature.

[rrousselGit]

Could you explain why Bloc needs it? I don't get it.
As it is, this proposal feels like the wrong solution to whatever problem you're having.

It could be that there's a separate solution that doesn't require changing copyWith.

For starter, if Dart had a built-in copyWith, it'd be very likely not to support this feature request.
So I'm on the fence about adding it to Freezed.