IssueTracker

Oh I forgot to mention that I thought it might be connected to this issue: https://issuetracker.google.com/issues/243778589. But after trying 2.5.2 I can say that the issue persists.

Please provide a minimal sample project along with the minimal steps to recreate the issue in the project.

Sorry for the delay. I got a working example here: https://github.com/Del-S/issues. The project is set up to crash when navigating to ThirdFragment (nested nav graph) with poping the graph.

I poked into it a little bit and it seems to be connected to SafeArgs gradle plugin. When safe args is used to navigate to ThirdFragment (with nested graph poped) it will try to recreate te parent but there were no arguments passed so it crashes.

Steps to reproduce:

1. Navigate from Second Fragment to Child nav graph (with non-nullable parameters).
2. Navigate to Third fragment using SafeArgs and the app crashes.

Crash log:

Process: cz.dels.issues, PID: 1743
java.lang.NullPointerException: null cannot be cast to non-null type kotlin.Long
at androidx.navigation.NavType$Companion$LongType$1.get(NavType.kt:352)
at androidx.navigation.NavType$Companion$LongType$1.get(NavType.kt:342)
at androidx.navigation.NavArgument.verify(NavArgument.kt:76)
at androidx.navigation.NavDestination.addInDefaultArgs(NavDestination.kt:502)
at androidx.navigation.NavController.addEntryToBackStack(NavController.kt:1865)
at androidx.navigation.NavController.addEntryToBackStack$default(NavController.kt:1813)
at androidx.navigation.NavController$navigate$4.invoke(NavController.kt:1721)
at androidx.navigation.NavController$navigate$4.invoke(NavController.kt:1719)
at androidx.navigation.NavController$NavControllerNavigatorState.push(NavController.kt:287)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.kt:246)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.kt:162)
at androidx.navigation.NavController.navigateInternal(NavController.kt:260)
at androidx.navigation.NavController.navigate(NavController.kt:1719)
at androidx.navigation.NavController.navigate(NavController.kt:1545)
at androidx.navigation.NavController.navigate(NavController.kt:1472)
at androidx.navigation.NavController.navigate(NavController.kt:1930)
at cz.dels.issues.SecondFragment.onViewCreated$lambda-0(SecondFragment.kt:38)
at cz.dels.issues.SecondFragment.$r8$lambda$XDYnOS_cYrafiNQ5rcCu1WCn0IE(Unknown Source:0)
at cz.dels.issues.SecondFragment$$ExternalSyntheticLambda0.onClick(Unknown Source:2)

Note: If in step 2 SaveArgs is not used then navigation works correctly. More information is here: https://github.com/Del-S/issues/blob/master/app/src/main/java/cz/dels/issues/SecondFragment.kt#L37.

Ups a typo: Navigate from Second First Fragment to Child nav graph (with non-nullable parameters).

Note: sorry for the spam but I am not able to edit my own comment.

This has been fixed and will be available in navigation 2.6.0-alpha08

The following release(s) address this bug.It is possible this bug has only been partially addressed:

• androidx.navigation:navigation-runtime:2.6.0-alpha08

If you are using hilt you can wrap the incoming arguments in fragment like so

open class BaseFragment : Fragment() {

    override fun setArguments(args: Bundle?) {
        if (args != null) {
            super.setArguments(Bundle(args).apply {
                putBundle(BUNDLE_ARGS, args) // Wrap the arguments as BUNDLE_ARGS
            })
        } else {
            super.setArguments(null)
        }
    }
}

and then for the view model, you can inherit from something like that

open class ArgsViewModel(private val savedStateHandle: SavedStateHandle) : ViewModel() {

    val arguments get() = savedStateHandle.get<Bundle>(BUNDLE_ARGS)

    @MainThread
    inline fun <reified Args : NavArgs> navArgs() = NavArgsLazy(Args::class) {
        arguments ?: throw IllegalStateException("ViewModel $this has null arguments")
    }
}

Hope that helps

Should be fixed by https://github.com/androidx/androidx/pull/122

Do you know when this will be released?

Re #11 - The public hotlist listed at the top of this bug says "androidx-navigation-2.4.0-alpha01" - that's the expected release.

It seems this has been included in the 2.4.0-alpha01 release.

But is there any additional setup required besides updating the navigation dependencies? With the following dependencies on my project

object Navigation {
    private const val version = "2.4.0-alpha01"
    const val compose = "androidx.navigation:navigation-compose:$version"
    const val fragment = "androidx.navigation:navigation-fragment-ktx:$version"
    const val safeArgsPlugin = "androidx.navigation:navigation-safe-args-gradle-plugin:$version"
    const val ui = "androidx.navigation:navigation-ui-ktx:$version"
}

my safeargs don't generate fromSavedStateHandle().

fromBundle() is still the only auto-complete suggestion.

FooFragmentArgs.fromSavedStateHandle(savedStateHandle) is an unresolved reference in my ViewModel.

Re #13, #14 - please upgrade to the latest version of Android Studio and file a bug against Android Studio if you are still not seeing this method in the Studio generated light classes.

I'm using Arctic Fox | 2020.3.1 Canary 9. I've just updated Navigation to 2.4.0-alpha02 and still seeing the bug, so I've filed a bug against AS. https://issuetracker.google.com/issues/189966590

As mentioned in the linked issue, manually downloading the latest version of Android Studio Preview fixes the issue