Hey there, tried searching for this, but wasn't ab...

# rx

[nic]

Hey there, tried searching for this, but wasn't able to pull any results. What's the best way to take an Observable, FlatMapSingle to a Single Observable, but wait until we receive the result of the Single Observable, and decide to either complete or move onto the next one.
For example:

getSomeObservable().flatMapSingle { t -> performAPICallWithData(t) }

I don't want to performAPICallWithData until the first one has completed, and I want to use the result from performAPICallWithData to determine wether I should perform the next one or complete everything

[alexsullivan114]

Could you do something like:

val observable = getSomeObservable().share()

observable.take(1).switchMap { t -> performApiCallWithData(t).flatMap { if (it.rightKindOfData) observable.skip(1) else Observable.empty() }

[alexsullivan114]

You don't really need switchMap there since that'll probably not compile because you're using a single. Could just be flatMap, doesn't make a difference in this case

[nic]

Thanks for the feedback! I ended up going with something like this for now

getSomeObservable().map { t ->
performApiCallWithData(t).blockingGet()
}.takeWhile {
 !it.rightKindOfData 
}.ignoreElements()

Seems to be working at the moment, although I'm open to alternative approaches. Does that make sense to you?

[alexsullivan114]

It does, though it's always best to work to avoid blockingGet since it defeats a bit part of the purpose. That being said if it works at this point I'd say it's fine.

[nic]

It bugged me enough to spend more time on it, and I think the most elegant solution is using concatMapSingleDelayError which seems to work perfectly.

it ends up like

getSomeObservable().concatMapSingleDelayError { t ->
performApiCallWithData(t)
}.takeWhile {
 !it.rightKindOfData 
}.ignoreElements()

[nic]

The documentation is

Maps the upstream items into SingleSources and subscribes to them one after the other succeeds or fails, emits their success values and delays all errors till both this Observable and all inner SingleSources terminate.

which is exactly what I was looking for. The key term being subscribes to them one after the other succeeds or fails

[alexsullivan114]

awesome!