Hello guys! I want to collect shared flow from vie...

# compose

[Sanendak]

Hello guys! I want to collect shared flow from viewModel, but it works only one time.

val scope = rememberCoroutineScope()

LaunchedEffect(scope) {
        viewModel.effect.collect {
            when(it) {
               is ShowEffect1 -> //Runs first from VM and shows
               is ShowEffect2 -> //Runs after and doesn't run here
            }
        }
    }

In ViewModel:

private val _effect = MutableSharedFlow<CharactersScreenEffect>()
val effect = _effect.asSharedFlow()

I don't want to use .asStateFlow because it need initial state.

[Zach Klippenstein (he/him) [MOD]]

What do you do in the ShowEffect1 case?

[Sanendak]

It shows snackbar. If I use asStateFlow with "Idle" initial state it works perfectly

[Zach Klippenstein (he/him) [MOD]]

Can you show more code?

[Zach Klippenstein (he/him) [MOD]]

Also, you don’t need to use rememberCoroutineScope with LaunchedEffect

[Sanendak]

LaunchedEffect(scope) {
    viewModel.effect.collect { effect ->
        when (effect) {
            is CharactersScreenEffect.ShowSnackbar -> {
                snackbarState.showSnackbar(
                    message = effect.character,
                    actionLabel = "Dismiss",
                    duration = SnackbarDuration.Indefinite
                )
            }
            CharactersScreenEffect.CloseSnackbar -> {
                snackbarState.currentSnackbarData?.dismiss()
            }
        }
    }
}

Full code

[Sanendak]

Forgot about snackbar state

val snackbarState = remember { SnackbarHostState() }

[Zach Klippenstein (he/him) [MOD]]

showSnackbar suspends until the snackbar goes away. If that second emission comes while the snackbar is still showing, it won’t be delivered to your collector because it’s still suspended. If you wrap snackbarState.showSnackbar in a launch, i think it will fix it.

[Sanendak]

Thanks, but it not fixed it

[Zach Klippenstein (he/him) [MOD]]

Another thing: instead of passing scope to LaunchedEffect (which is effectively a no-op), you might want to pass viewModel.effect since that’s the object you’re operating on inside the effect. E.g. If, for some reason, the view model would ever return a different effect, you’d need to cancel collecting on the old one but not the new one.

[Sanendak]

Damn, my bad. Your suggestion fixed my problem. Thanks!