Extracting navigation args at destination activity when using type safe navigation

Question

I am using navigation component's type safe APIs to navigate. The app which I inherited uses several activities (2-3), and fragments everywhere else. One of the flows requires to navigate from a fragment of one activity to another activity. This works ok when I declare my graph destinations like so:

//Routes.kt
@Serializable
data class SecondScreen(val foo: Foo, val bar: String = "")
//FirstActivity.kt
findNavController().createGraph(SomeStartDestination) {
 activity<SecondScreen>(
 typeMap = mapOf(
 typeOf<Foo> to NavType.EnumType(Foo::class.java)
 )
 ) {
 activityClass = SecondActivity::class
 }
}
//SecondActivity.kt
fun onCreate() {
 val route = findNavController().currentBackStackEntry?.toRoute<SecondScreen>()
 print(route?.foo) // null
 print(route?.bar) // null
}

The part that does not work is retrieving the args that were passed along. I suspect that when the SecondActivity gets created, its NavHost and NavController start out with an empty backstack. If I grab the intent extras, it seems to extract the data ok, yet I feel that it's more of a workaround than an idiomatic solution. I looked around but did not come across any documentation for such a scenario. Am I missing something?

• NirajDota: The type safe navigation is made for single activity architecture in Jetpack Compose. It's meant to navigate you from a composable route to another composable route. Intent passing is still needed when going from activity to another.
• Edric: If I'm not wrong, the arguments should still be passed in the activity intent's arguments - try logging the value of intent.arguments to verify

Answer 1

• If you want findNavController.currentBackStackEntry?.toRoute<T>() to work in the activity,call navcontroller.setGraph(..., inten.extra) early in onCreate .

• If you only need the arg in activity, read intent.extra directly (clean & simple).

Here is example to set Nav graph with inten.extras So toRoute<T>() works.

When the activity starts, pass the incoming Intent.extras to NavController via setGraph(graphResId,startDestinationArg) (or setGraph(NavGraph,bundel)).

// Get NavController from NavHostFragment
val navHost = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
val navController = navHost.navController
// Option A: if graph is defined as resource, pass intent.extras when setting graph
navController.setGraph(R.navigation.your_graph, intent.extras)
// Option B: if you already have a NavGraph instance, do:
// navController.setGraph(navController.graph, intent.extras)
// Now the NavController has the startDestination entry populated with arguments
val route = navController.currentBackStackEntry?.toRoute<SecondScreen>()
Log.d("Args", "route foo=${route?.foo} bar=${route?.bar}")

Second Activity class , Put below code in onCreate Method
// If your route is serializable/Parcelable or you know how args were packed,
// this is the direct way:
val extras = intent.extras
extras?.let {
 // If you used a single-bundle-arg convention, convert it:
 val route: SecondScreen? = extras.toRoute() // if you have helper
 // or extract each arg:
 val bar = extras.getString("barArgName")
 val foo = extras.getSerializable("fooArgName") as? Foo
}

Try above solution
Thank you