hi I'm using navigation compose & my requirement is to have startDestination as list or detail p...

# compose

[Ravi]

hi I'm using navigation compose & my requirement is to have startDestination as list or detail page. Got no issues with list but for detail I need to pass detail id, more in the thread

[Ravi]

@Composable
fun NavGraph(startDestination: String = DEST_LIST) {
    val navController = rememberNavController()
    NavHost(navController, startDestination = startDestination) {
        composable(
            route = DEST_LIST,
        ) {
            Column {
                repeat(5) {
                    Text(text = "List Item : $it")
                }
            }
        }
        composable(
            route = "$DEST_DETAIL/{$ARG_DETAIL_ID}",
            arguments = listOf(navArgument(ARG_DETAIL_ID) { type = NavType.LongType })
        ) {
            // Load Detail
            Text(text = "ARG_DETAIL_ID: ${it.arguments?.getLong(ARG_DETAIL_ID)}")
        }
    }
}

const val DEST_LIST = "listDestination"
const val DEST_DETAIL = "detailDestination"
const val ARG_DETAIL_ID = "detailId"

[Ravi]

if i change startDestination to

startDestination: String = "$DEST_DETAIL/1"

app is crashing

java.lang.IllegalArgumentException: navigation destination 1678697370 is not a direct child of this NavGraph

[Ravi]

is this correct way to do it?

[Ian Lake]

The startDestination needs to match the route exactly, so you should be using "$DEST_DETAIL/{$ARG_DETAIL_ID}"

[Ian Lake]

But you should never, ever be changing the startDestination like that as per the Principles of Navigation: https://developer.android.com/guide/navigation/navigation-principles#fixed_start_destination

[Ian Lake]

Something specifically pointed out in the Navigation Compose guide: https://developer.android.com/jetpack/compose/navigation#create-navhost

[Ian Lake]

What are you trying to accomplish?

[Ravi]

I'm trying to pass startDestination with id to launch details screen first.

startDestination: String = "DEST_DETAIL/{$id}"

some thing like this id will be Long

[Ian Lake]

I think we're having an XY Problem: https://xyproblem.info/

[Ian Lake]

Can you explain your use case from the base level?

[Ravi]

DetailActivity gets detail_id as argument and this particular activity got 3-4 composables under navgraph. I've to pass this detail_id as startDestination to launch detail composable. If I'm using fragments i get these args through navArgs . Is there similar mechanism for composables navgraph?

[Ravi]

i can create sample project to explain this scenario

[Ian Lake]

I'm confused. What does passing arguments have to do with the startDestination? Changing the start destination is not how you navigate between destinations - you'd want to follow the docs on how to navigate with arguments

[Ravi]

https://gist.github.com/ravitejasc/0c3138684cca8325b0dc417dbfa8cc9d plz have a look

[Ian Lake]

This gist does not match your initial statement of "my requirement is to have startDestination as list or detail page" at all. Is that original statement actually not the case?

[Ravi]

ya, sry for the confusion i just need to launch detail composable with the activity's bundle argument.

[Ian Lake]

well, then you have two choices:
• Add a deepLink to your destination. NavController will automatically check your Intent for a matching deep link (looking at the data field of the Intent) and parse arguments out of that deeplink, starting that destination with the correct arguments. This is my recommendation
• Set a defaultValue on your navArgument, not touching the startDestination at all

[Ravi]

ty @Ian Lake ill try first approach