Can I cancel collecting a `StateFlow` from within the `collect` function? Let's say I received the v...

# coroutines

[Lukasz Kalnik]

Can I cancel collecting a StateFlow from within the collect function? Let's say I received the value I expected and want to stop collecting.

[kevin.cianfarini]

Why wouldn't you do something more idiomatic like

stateFlow.first { it == theValue }

[Lukasz Kalnik]

Oh yes, that's much better!

[Lukasz Kalnik]

I want to run an action when I get the value, so I assume first just suspends until the condition is true and I can call my action afterwards?

[Lukasz Kalnik]

coroutineScope.launch {
    stateFlow.first { it }
    action()
}

[Lukasz Kalnik]

I'm just waiting for the stateFlow to become true

[Lukasz Kalnik]

Thanks for your quick help 🙏

[kevin.cianfarini]

I would say your sample is fine

[CLOVIS]

You can also

stateFlow
    .filter { it == theValue }
    .onEach { yourAction() }
    .first()

Your call on which is more readable

[kevin.cianfarini]

I personally dislike onEach because it’s inherently side effecty but either works

[CLOVIS]

I want to run an action when I get the value

Well that's the definition of a side effect, isn't it?

[Lukasz Kalnik]

Although just using first is more concise.

[jw]

No it's the definition of an effect. A primary effect.

[jw]

Side effects are like logging

[ephemient]

btw the usual way to "stop" collecting is with takeWhile or transformWhile, but if you're only interested that it exists at all, then first followed by non-Flow code is simplest