I've got a rather callback-heavy API, which I've m...

# coroutines

[reactormonk]

I've got a rather callback-heavy API, which I've modeled roughly as

fun onReaderConnected(): Flow<Reader> { ... }
class Reader {
  fun onCard(): Flow<Card>
}

And I'm consuming it via

onReaderConnected() { reader ->
  reader.onCard().collect {
    ... process card ...
  }
}

Now I've run into the issue where the reader disconnects, the inner collect won't stop, so the new reader connection won't get activated. How do I best model that?

[simon.vergauwen]

Why are you not using flatMap in this case? 🤔

val x: Flow<Unit> = onReaderConnected().flatMapConcat {
  reader.onCard().map {
    /** process card */
  }
}

Or flatMapLatest based on desired behavior

[simon.vergauwen]

Then you can use collect() or launchIn at the edge.

[reactormonk]

flatMapLatest looks exactly what I'm looking for, thanks! Now to figure out why it doesn't behave as it should 🤔

[louiscad]

collectLatest might also do the trick depending on whether you need the end result in a Flow.