rx - Conditional flatMap / add condition to flowable boolean

Question

I need to show error view if status is error and call.isEmpty() returns true.

Is there a better way to achieve this result?

val errorVisible = states.asFlowable()
    .map { it.status == Status.ERROR }
    .flatMap { isError ->
        if (isError) call.isEmpty()
        else Flowable.just(false)
    }

call.isEmpty() returns Flowable<Boolean> but can return something else like Single<Boolean>.

EDIT: Another question, if call.isEmpty() returns Flowable<Boolean> how can I merge two streams (two Flowable<Boolean>s - states.isError and call.isEmpty()) and map it to one Flowable<Boolean> so it's one condition?

well, you don't need to use `map` and put both conditions into `flatMap` if this is what you're asking — martin, Sep 02 '18 at 19:53
@martin Yes, I can skip `map` in this case. But I was looking for a different, possibly better way of doing the same thing by changing `flatMap`. My end goal is to return `Flowable` when it's `isError` and `call.isEmpty()`. — alashow, Sep 02 '18 at 19:58

score 3 · Answer 1 · answered Nov 28 '19 at 14:25

3

You can break the condition

.flatMap {
  if (it.isEmpty()) {
    Observable.empty()
  } else {
    Observable.just(true)
  }
}

answered Nov 28 '19 at 14:25

tharinduPro

99
1
6

score 1 · Answer 2 · answered Oct 03 '18 at 15:31

1

Maybe you can use something like this

val errorVisible = states.asFlowable()
        .onErrorReturn { true }
        .flatMap { Flowable.just(it.status == Status.ERROR) }

answered Oct 03 '18 at 15:31

Constantin Chernishov

291
1
7

Where is `call.isEmpty()`? See https://stackoverflow.com/a/52140849/2897341 – alashow Oct 03 '18 at 17:41

score 0 · Answer 3 · answered Sep 02 '18 at 20:36

0

You could use a when or if block:

val errorVisible = states.asFlowable()
    .flatMap {
        when(it.status) {
            Status.ERROR -> call.isEmpty()
            else -> Flowable.just(false)
        }
    }

answered Sep 02 '18 at 20:36

ESala

6,878
4
34
55

I was looking more of an RX way of doing this if there is any. BTW, I also added a new question. – alashow Sep 02 '18 at 20:52

rx - Conditional flatMap / add condition to flowable boolean

3 Answers3