Hello all, I have a question about the best approach to handling conditional/if-else situation. I have an API response that will return one of three classes:

Loading

,

Error

, or

Finished

— all of which inherit from a class called:

NetworkState

. If its Loading or Error, I want to update my UI appropriately. If its finished, I need to extract the data, do further transformations, then update the UI. I also need to perform a side-effect depending on one of the values returned. I can think of two ways to do this. Which of these is preferable? Is there a better third option? OPTION 1

fetchFromApi().
  .map {
    when (it) {
      is Loading -> transformToLoadingView()
      is Error -> transformToErrorView()
      is Finished -> mapDataToUI(it.data)
  }.subscribe { view -> updateUi(view) }

fun mapDataToUI(data: Data) {
  performSideEffect(data)
  transformDataToView(data)
}

OPTION 2

val sharedResponse = fetchFromApi().share()

Observable.merge(
  sharedResponse.ofType('Loading').map { loadingView },
  sharedResponse.ofType('Error').map { errorView },
  sharedResponse.ofType('Finished').map { transformDataToView(it) }
).subscribe { view -> updateUi(view) }

sharedResponse.ofType('Finished').subscribe { performSideEffect(it) }

option 1 is much easier to read, tho, less noisy. Unrelated, but I've never understood why people use

loading

in result of the api call simple smile. Don't you always know that you're loading when you subsribe?

I agree its easier to read; however what’s more consistent with sortof the “philosophy” of Rx? (also unfortunately the loading thing is outside of my control — agree its not great)

The

Loading

State is just for keeping the whole application state inside the viewModel instead of letting the view to decide if it is loading or not.

@edwardwongtl any thoughts on the above two options?

2 could be dont without the share, with publish that takes a function

I would say I prefer 1