Hi. I am playing around with navigation in compose, but with no known pages. The idea is to have only one route

page/{pageName}

and then use

pageName

to to render the correct data. I mostly wanted to use navigation because of the built in backstack

@Composable
fun NavigationTest() {
    val navController = rememberNavController()
    Scaffold(
        bottomBar = { SimpleBottomNav(navController) }
    ) { innerPadding ->
        NavHost(navController, startDestination = "page/{pageName}", Modifier.padding(innerPadding)) {
            composable(
                "page/{pageName}",
                arguments = listOf(navArgument("pageName") { defaultValue = "profile" })
            ) { backStackEntry ->
                val pageName = backStackEntry.arguments?.getString("pageName")
                if (pageName != null) {
                    PageContent(name = pageName)
                } else {
                    Text(text = "No page name")
                }
            }
        }
    }
}

See

SimpleBottomNav

code in the comments. The main issues that I have is that 1.

popUpTo()

does not seem to work properly when the startDestination has an argument in it and 2. the compose context seems to be shared between the different pages. E.g. when i use a LazyList in them, they all share the same scroll state. Did anyone ever have the same issues or has a working example for something similar?

You have to have "known pages". Can you explain why you think you don't know what pages you have?

the pages are server driven and dynamic.

pageName

is used inside `PageContent`'s VM to load the data (page names are loaded dynamically too at app start). This works great, but like i mentioned, I am mostly looking for a way to preserve the page state in a backstack when navigating away so it can be restored when navigating back. Navigation has that build in and i was hoping I could use it. I mean, one page is known, i just add an argument to define its data. Are you saying this is not the intended use of navigation?

The navigation graph is just code - you can load everything from the server and use that information to construct your graph, but you need each destination to be in your graph

Unfortunately I can't define any pages beforehand. It's all the same composable that changes its look according to the data loaded with the pageName. So the navigation graph is only one node with the added parameter

It's all the same composable that changes its look according to the data loaded with the pageName

That sounds like different composables. Specifically, different composables using a slot based API

right, i have the bottom nav hardcoded in above example, but in reality, they are also loaded dynamically on app start I don't know how many there are nor what pages they show. And yes, the

PageContent

composable plugs together different existing composables, but not in a way that they could be defined as navigation targets. Assume they are completely dynamic - they could contain just one composable, a list, grid or anything else.

Let's take your bottom nav as an example. You absolutely can have a server provide you a list of bottom nav items, do a for each loop, and add them all to your graph as separate destinations. It is Kotlin code, so you can use any Kotlin control syntax

FWIW I have a fully server driven app built in prod BUT the nav graph is deterministic, but each "screen" composable is the same. But having a concrete nav graph definitely simplified things. If your nav graph and everything is essentially server driven as well then I think you might be better off just handling navigation/backstack yourself? @ ian in the activity world, you could have multiple activities one on top of another. like. activityA launches activityA, which launches activityA. From what it sounds like you said above, that's not possible with Compose "screen" destinations? If you have destinationA launch destinationA, then you wouldn't have a stack.size=2?

Oh, you can absolutely have multiple copies of a single destination in a row (there's even that special flag,

launchSingleTop

, if you want to disable that behavior)

ah i think i am finally understanding what you are saying. tried that real quick with only the bottomNavTabs and it works great. question is, how can i modify the graph later one? I don't know all possible destination at this point. New destination need to be added as the user clicks though the app. Only thing i could imagine is to use a state or a flow that emits am updated list of destinations and then rebuild the whole graph?

You need to get rid of the

page/$pageName

syntax - just use

pageName

as the route:

fun NavigationTest() {
    val navController = rememberNavController()
    Scaffold(
        bottomBar = { SimpleBottomNav(navController) }
    ) { innerPadding ->
        val bottomNavTabs = getServerBottomNavTabs()
        NavHost(
            navController, 
            startDestination = bottomNavTabs[0], 
            Modifier.padding(innerPadding)
        ) {
            // Your bottom nav tabs use a fixed route
            bottomNavTabs.forEach { pageName ->
                composable("$pageName") {
                    PageContent(name = pageName)
                }
            }
            // These are your completely dynamic screens that don't have a fixed route
            composable("page/{$pageName}) { backStackEntry ->
                val pageName = backStackEntry.arguments?.getString("pageName")
                if (pageName != null) {
                    PageContent(name = pageName)
                } else {
                    Text(text = "No page name")
                }
            }
        }
    }
}

Ah yes definitely. That's just something I played around with. I think i can probably remove them for both, the bottom nav destination as well as the dynamic ones too