Hi all, looking to get a sanity check on lifecycleScopes… My Fragment is doing a simple network requ...

# android

[luke_c]

Hi all, looking to get a sanity check on lifecycleScopes…
My Fragment is doing a simple network request , and when it’s successful I’m navigating to another Fragment, when it fails I’m displaying an error

This works fine with process death, because the scope gets cancelled, but when the user backgrounds the app the coroutine still runs (because the view isn’t destroyed) and if successful it tries to navigate to the Fragment which fails because it’s after onSaveInstanceState()

Is this the ‘correct’ approach below, to basically wrap the Fragment transaction in whenStarted?

viewLifecycleOwner.lifecycleScope.launch {
    val response = fetchConfig()
    when (response) {
        is ConfigResponse -> {
            whenStarted {
                goToNextScreen()
            }
        }
        Error -> showError()
    }
}

[Martyna Maron]

How does whenStarted help here? If you background the app and let the coroutine finish, on foregrounding the app, is goToNextScreen() triggered?

According to the docs should the fetchConfig be wrapped in whenStarted too? 🤔

[luke_c]

Yes that’s right, if I don’t use whenStarted then goToNextScreen() gets triggered when the app is in the background leading to an exception

[Adam Powell]

There's some new stuff WIP in lifecycle-runtime-ktx that you might find useful: https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:lifecycl[…]a/androidx/lifecycle/RepeatOnLifecycle.kt?q=repeatOnLifecycle