I want to collect `navController.currentBackStackEntryFlow` and must to do it in CoroutineScope. I h...

# compose

[iamthevoid]

I want to collect navController.currentBackStackEntryFlow and must to do it in CoroutineScope. I have few questions
1. Where can I read about relation of coroutines and composables
2. Where better to collect this flow? Looks like there are mechanisms in compose to handle coroutines, but i am not sure that good practice to do as i did.
3. Even if it is good practice - what is better to use as key for LaunchedEffect ? I select activity, but it seems meaningless

[Dominaezzz]

There are better ways to write that. Checkout collectAsState .
If you give me a copy/pastable snippet, I can show you.

[iamthevoid]

You definitely mean

val route by navController.currentBackStackEntryFlow
  .map { it.destination.route.orEmpty() }
  .collectAsState(initial = START_ROUTE)

Got it. Thanks

[Dominaezzz]

Pretty much. Just need to add a remember there.

val route by remember(navController) {
   navController.currentBackStackEntryFlow
  .map { it.destination.route.orEmpty() }
}
  .collectAsState(initial = START_ROUTE)

[iamthevoid]

Can you please explain what difference is?

[Adam Powell]

The difference is explained here https://kotlinlang.slack.com/archives/CJLTWPH7S/p1622294790253600?thread_ts=1622294790.253600&cid=CJLTWPH7S

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

If you’re looking for things to read, I’d start here: https://developer.android.com/jetpack/compose/side-effects

[Ian Lake]

Note that there's is already a currentBackStackEntryAsState() method that does the right thing: https://developer.android.com/reference/kotlin/androidx/navigation/compose/package-summary#(androidx.navigation.NavCon[…]rentBackStackEntryAsState()

val currentRoute = navController.currentBackStackEntryAsState()?.destination?.route ?: START_ROUTE