Accessing parameters passed via kotlin NavHost at the destination

Question

I am writing an app that uses androidx.navigation to navigate between screens, and following this documentation:

https://developer.android.com/guide/navigation/design/kotlin-dsl

I'm struggling to understand how to access parameters at the destination.

My (simplified) screen route looks like:

@Serializable
data class TimerEntryRoute(
    val operation: String,
...
)

I'm instantiating a route object in my NavHost with my parameter:

NavHost(
        navController = navController,
        startDestination = HomeRoute,
        modifier = modifier
    ) {
        composable<HomeRoute> {
            HomeScreen(
                navigateToTimerEntry = { navController.navigate(route = TimerEntryRoute(operation = "ENTER")) }
            )
        }
    }
}

How can I then access that route object to receive my parameters at the destination? Do I have to use the back-stack toRoute function? Does the destination need to be passed the navController to do so? It seems there ought to be a cleaner way.

Answer 1

  NavHost(
            navController = navController,
            startDestination = HomeRoute,
            modifier = modifier
        ) {
            composable<HomeRoute> {
                HomeScreen(
                    navigateToTimerEntry = { navController.navigate(TimerEntryRoute(operation = "ENTER")) }
                )
            }

            composable<TimerEntryRoute> { navBackStackEntry ->

                // Retrieve the route parameters directly

                val route = navBackStackEntry.toRoute<TimerEntryRoute>()
                TimerEntryScreen(
                    operation = route.operation

                )
            }
        }

• Use navBackStackEntry.toRoute() to retrieve the route parameters.
• You don't need to pass the navController to the destination screen unless you specifically need it for navigation actions.
• The toRoute() function is provided by the navigation library and allows you to directly extract the route parameters.