Unhandled Exception: type 'SetEventItemFailAction' is not a subtype of type 'FutureOr<UpdateTaskAction>' about dart_redux_epics HOT 3 CLOSED

Update:

I solved this problem in this way:

Stream<dynamic> setEventItemsEffect(
    Stream<dynamic> actions, EpicStore<AppState> store) {
  return actions
      .whereType<SetEventItemAction>()
      .asyncMap((action) => handleEventItems(action.task)
        .then<dynamic>((res) => UpdateTaskAction(task: action.task)
        .catchError((_) => SetEventItemFailAction(task: action.task))
  );
}

Is there a better way? @brianegan

from dart_redux_epics.

Hey there -- Futures can only return one type of Object. In your original example, Dart is inferring that you want to create a Future<UpdateTaskAction>, but if an error occurs you're trying to return a different type: SetEventItemFailAction. The future cannot do that -- it can only return one type!

Therefore, you have two options:

1. Make each of these action classes implement a common parent interface
2. Use Object or dynamic as a default parent interface -- which is what Redux does, and what you've done!

Therefore, the way you've solved it is completely appropriate, but hope this explanation helps you understand why :)

from dart_redux_epics.

Hey there -- Futures can only return one type of Object. In your original example, Dart is inferring that you want to create a Future<UpdateTaskAction>, but if an error occurs you're trying to return a different type: SetEventItemFailAction. The future cannot do that -- it can only return one type!

Therefore, you have two options:

1. Make each of these action classes implement a common parent interface
2. Use Object or dynamic as a default parent interface -- which is what Redux does, and what you've done!

Therefore, the way you've solved it is completely appropriate, but hope this explanation helps you understand why :)

Thank you very much for your explanation.

from dart_redux_epics.