I have a `Channel` that I'm converting to a flow and listening to. As soon as the channel is create...

# coroutines

[alexsullivan114]

I have a Channel that I'm converting to a flow and listening to. As soon as the channel is created I'm sending through an initial default value. Right before that happens I'm observing the flow using the onEach pattern. The flow, however, is not receiving the initial value, presumably because there's an asynchronous launch involved. Does anyone have any idea how to get around this issue?

[octylFractal]

I don't think onEach observes the flow at all? are you eventually calling a terminal op like launchIn or collect?

[alexsullivan114]

Sorry yes I'm calling launchIn

[octylFractal]

not sure then, if you can provide an example that reproduces the issue I can look a little further

[alexsullivan114]

Sure, one minute

[alexsullivan114]

object Woofers {
  fun doStuff(scope: CoroutineScope) {
    val channel = BroadcastChannel<Int>(Channel.BUFFERED)
    channel
        .asFlow()
        .onEach { println("Value: $it") }
        .launchIn(scope)

    // Won't be received
    channel.offer(1)
  }
}

[alexsullivan114]

That repros it

[octylFractal]

yea, it looks like an ordering thing. I tried a few tricks, but I don't know if there's an easy way around it

[octylFractal]

if it works for you, using flow.onStart { emit(1) } might be a better solution

[streetsofboston]

Is it only the first emission/value that goes missing?

[streetsofboston]

What if you tried a regular Channel instead of a BroadcastChannel?
I don’t see a reason why that would work, but i’m just curious 🙂

[alexsullivan114]

I ended up using`flow.onStart`which worked. It could be more than the first value - presumably its all of the values until the launch call is up.

I haven't tried a regular Channel I'll see if that makes a difference