Why emitting state resets state variable in flutter cubit

Question

I am using cubit for state management. And i have a variable in the state. And it gets resetted when some other state is emitted.

state_file

class UserState extends Equatable {
  final SampleModel? sampleModel;
  const UserState({this.sampleModel});
  UserState copyWith({String? name, String? avatar}) {
    return UserState(
        sampleModel: SampleModel(
            name: name ?? sampleModel?.name ?? "",
            avatar: avatar ?? sampleModel?.avatar ?? ""));
  }

  @override
  List<Object?> get props => [sampleModel];
}

class UserMainLoadingState extends UserState {}   // this resets my sampleModel why ?

class UserSavedUpdatedState extends UserState {   // One way around is by sending props in every state
  UserSavedUpdatedState({required SampleModel sample})
      : super(sampleModel: sample);
}

cubit_file

 Future<void> addSampleUser({required SampleModel sample}) async {
    print("I am inside this add sample");
    print("State is ${state.sampleModel!}");   // prints sampleModel
    emit(UserSideLoadingState());
    print("State is ${state.sampleModel!}");   // Null check operator used on a null value
 }

Why this happens, and how to overcome this without passing props to every state.

Answer 1

It's resetting because when you emit UserMainLoadingState you are not copying SampleModel from the previous state, so it's lost. Simple solution would be:

class UserMainLoadingState extends UserState {
  const UserMainLoadingState({required SampleModel sample})
      : super(sampleModel: sample);
}