Hi. I had original <question about compose destina...

# compose

[Tomáš Procházka]

Hi. I had original question about compose destination library, but it looks that it is not specific to that library but the same issue is even with androidx.navigation.compose.NavHost . There is also no way how to directly open target destination from deeplink without opening startDestination . So it is basically the same problem. Why there is no way to put deepLinkUri as initial destination for NavHost 😞. Even navController.findDestination() can't accept deep link 😞

[Ian Lake]

Everything you're saying is incorrect. NavHost automatically handles deep links from your Activity's Intent, you don't need to write any code for that case. When handling a deep link, the start destination is not invoked at all, but it is used to create the synthetic back stack of the deep linked destination.

See the docs that explain the automatic handling and the sythetic back stack parts:
https://developer.android.com/guide/navigation/design/deep-link

[Tomáš Procházka]

Problem is that I'm not in activity directly, in my case the origin is Fragment.
So I need to replicate the same behavior, but in Fragment. 😞

[Tomáš Procházka]

I need to found where exactly is that Activity's Intent handled, that it happen before invoking start destination. So far I was not successful.

[Ian Lake]

The onGraphCreated is what is called once the graph is set (via the NavHost) and any state is restored. If there wasn't any state to restore, it checks whether it needs to handle a deep link and otherwise goes to the start destination: https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:navigati[…]otlin/androidx/navigation/internal/NavControllerImpl.kt;l=971

[Ian Lake]

Where the checkDeepLinkHandled on Android calls handleDeepLink with the Activity's intent: https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:navigati[…]ain/kotlin/androidx/navigation/NavController.android.kt;l=481

[Ian Lake]

But you shouldn't be using deep links when you are internal to your app, so I think what is actually happening is an XY Problem: https://en.wikipedia.org/wiki/XY_problem

Where you're running into this issue 'Y' without explaining the 'X' of how you've set things up in the first place. Maybe taking a step back and talking through what you are trying to do at a base level would be helpful context?

[Tomáš Procházka]

Thanks I will investigate it.

To to the XY problem. It is hard. I'm working in corporate env. where many thing doesn't make any sense. We are using internal framework which purpose is to split one big app to many fully independent parts and then allows to build any app from them just by choosing independent features to it. It is based of XML nav graphs and fragments. It has many disadvantages, dev hate it, but sadly management likes it. It for example using internal deep links to navigate between that independent parts quite heavily.

And I'm trying to start migration to compose. So I want to allows to build fully compose features based on this and allows them to be used together with other that are fragment based. With "fully" I mean that I don't want to see any fragment or fragment navigation inside of it. So me whole feature will live inside of one Fragment with own compose based navigation. One time when all features will be compose we will remove also fragment navigation from the framework itself. But now it must cooperate. So if there is some deep link (internal or external) , it will start or update the MainActivity, that will switch to right fragment (feature) and inside of that fragment (feature) will be navigated to the right compose screen.

[Tomáš Procházka]

It really works only if that deeplink intent is in the activity, which is not in my case. I'm getting it by

val deepLinkIntent = requireArguments().getParcelable(
    NavController.KEY_DEEP_LINK_INTENT,
    Intent::class.java
)

inside of the fragment.

So I can do two thing
1. quite and dirty, just call this before NavHost and restore it after

(LocalContext.current as Activity).intent = deepLinkUri

2) override NavController and override handleDeepLink() and use own intent instead of the actiity one.

[Tomáš Procházka]

So sad, NavController is open and handleDeepLink() also, so it looks that create a custom controller is easy, but oficial rememberNavController using also

navigatorProvider.addNavigator(ComposeNavGraphNavigator(navigatorProvider))

where ComposeNavGraphNavigator is for some reason internal, which block any possible custom NavController