Hi After upgrading to `navigation compose 2 4 0 alpha05` my

Question

Hi After upgrading to `navigation compose 2 4 0 alpha05` my view model `init ` is called continuously Does anyone having the same issue I m using `hilt navigation compose 1 0 0 alpha03`

julioromano · Answer

Yes check this thread <https kotlinlang slack com archives CJLTWPH7S p1626960240270300>

Tin Tran · Answer

I ve already checked that thread I don t have any navigation inside SideEffect

julioromano · Answer

go down

julioromano · Answer

there s also the viewmodel thing

julioromano · Answer

basically what I think it s happening is when the crossfade animation is ongoing many composables will be continuously recomposed once each frame of the animation

julioromano · Answer

This means many composable calls which before alpha04 were happening just once are now happening more often if in some parts of our code we didn t take this particularly into account it will become source of issues now that the animations have been turned on

Tin Tran · Answer

This doesn t seems to be the case because my code is using `HiltViewModel` Shouldn t its lifecycle be managed by compose navigation as well

Tin Tran · Answer

My route look like this ```composable Screens Login route deepLinks = listOf navDeepLink uriPattern = Screens Login pattern Login viewModel = hiltViewModel navController = navController modifier = Modifier fillMaxSize ```

Tin Tran · Answer

Hilt will help me inject the viewmodel and other dependencies too so looks like hilt is not updated to work with new version of navigation compose

julioromano · Answer

I was using `hiltViewModel ` too I reverted to `viewModel ` only for the bug report You might wanna try to create a dummy viewmodel and get it with `viewModel ` to check if the issue is specific to `hiltViewModel `

julioromano · Answer

My hunch is that during crossfade animation the `Login` composable is being called multiple times which in turns calls `hiltViewModel ` multiple times If you re seeing multiple calls to the viewModel s `init` it might mean that the owner s lifecycle has already been torn down therefore `hiltViewModel ` creates a new instance of the viewModel instead of returning the last cached one

julioromano · Answer

Sometimes a workaround to this is to move the call to `hiltViewModel ` inside the `Login` composable I know this will impact testability coz you can t pass in another viewModel during tests but perhaps it can be helpful to debug the issue and then file a bug report

Tin Tran · Answer

I m trying narrow the issue root cause Turns out it s not the view model that is reinit but my navigation code is calling endlessly ``` Composable fun Login viewModel LoginViewModel val state by viewModel dataState collectAsState layout code when state is DataState LOADING gt Loading modifier = Modifier fillMaxSize background color = LoadingBlack is DataState SUCCESS lt gt gt Log i LOGIN Login success navController navigate Screens Home route popUpTo Screens Login route inclusive = true else gt viewModel reduce LoginEvent IDLE ```

Tin Tran · Answer

looks like it s got recompose infinitely so the success block is called again and again

julioromano · Answer

Yeah that `navigate` call should be put inside a LaunchedEffect or similar

julioromano · Answer

Yes maybe not infinitely but perhaps once each frame of the crossfade animation

Tin Tran · Answer

Make sense So it get called every frame and queue up

julioromano · Answer

Yes animations invalidate the screen content more often so recompositions happens a lot more during animations

julioromano · Answer

navigation calls are side effects so they should be put inside a LaunchedEffect or DisposableEffect lambda so that they are not repeatedly called on every recomposition

Tin Tran · Answer

Is it anti pattern if I pass the nav controller to the viewmodel and let it navigate instead

julioromano · Answer

e g ```is DataState SUCCESS lt gt gt LaunchedEffect state Log i LOGIN Login success navController navigate Screens Home route popUpTo Screens Login route inclusive = true ```

julioromano · Answer

gt Is it anti pattern if I pass the nav controller to the viewmodel and let it navigate instead It may break the lifetime scope of objects The Lifetime of a view model is wider than that of the navController obj which is tied to the fragment or activity lifetime If you do that and your activity fragment is recreated during a configuration change the viewmodel wont be recreated and might keep using an old instance of navController while the newly instantiated activity fragment will have a newer one

Tin Tran · Answer

Got it Thanks a lot for helping me I m new to android and there s so much to learn