Sharing global state with the array of child states

[damirstuhec]

Imagine the following state and views composition:

AppState
	Shows: IdentifiedArrayOf<Show>
	Tags: IdentifiedArrayOf<Tag>

Screen 1
List of Show states using ForEachStore.

Screen 2
Details of selected Show state, and a list of tags from a global Tags state, with the ability to attach tags to the selected show.

I want Tags to be a global state because it holds information about all tags available, which should be shared across all Show states.

I tried passing the Tags state to the Show state initializer, but any changes made to the Tags state are of course not propagated back up with this approach.

My question is, how could one structure the state to achieve the goal described above with TCA?

[Dmitriy_Ignatyev]

What about storing this states separately? Do you use Rx / Combine?

Using Rx, I do the following:
let tags: Observable = ...
let showsSource: Observable = ...

let shows = Observable.combineLatest(tags, showsSource).map { tags, showsSource -> T in
// mix Shows & Tags
}

The same can be done without Rx, may be with more difficulties

[damirstuhec]

@Dmitriy_Ignatyev thanks for sharing, but I'm using The Composable Architecture (TCA).

[Dmitriy_Ignatyev]

Oh, sorry, I missed that. Seems like Redux.
Is there an action like 'case tagsUpdate(tags: [Tag])'?

If yes, it can be done like this:

let reducer = Reducer<AppState, AppAction, AppEnvironment> { state, action, _ in
  switch action {
   case tagsUpdate(let tags):
     state.tags = tags
     state.shows = state.shows.map { $0.copy(withNewTags: tags) }
  }
}

extension Show {
  copy(withNewTags: [Tag]) -> Self {
    Self.init(...)
  }
}