I m trying to add a reset the saved bottom nav stack on dema

Question

I m trying to add a reset the saved bottom nav stack on demand Something like ```fun NavController navToBottomNavItem route String startFromStackRoot Boolean = false = navigate route how to use startFromStackRoot popUpTo DashboardScreenDestination route saveState = true launchSingleTop = true restoreState = true ``` The scenario in our app is there s a botom menu and there s a Dashboard stack app starts on that and a Shop stack The code above makes sure that when user navigates between different bottom bar items he isn t starting from the root of the stack but ends up where he left So far so good But there s one scenario where I want to go from Dashboard directly to the root of the Shop stack without restoring it s state E g using the `startFromStackRoot` param

Michal Klimczak · Answer

After trying a few different ideas and digging into the source code of NavController I m beginning to think it s not possible the way NavController NavOptions apis are designed Seems like these backstacks are stored inside `backStackStates` and we can t just e g find and clear a backstack by some id Just invoking `restoreState` conditionally will work it will start from root but the old Shop stack state will still remain saved and it will be restored on another occasion while what we want is for the fresh one to be saved

Michal Klimczak · Answer

Another idea was to switch to the other stack make it restore its state and then immediately popBackStack all the way up to the Shop stack root But that didn t work either probably due to some race condition

Ian Lake · Answer

FWIW NavController synchronously updates its state when you call navigate popBackStack etc There s no way to race since the state is already up to date

Michal Klimczak · Answer

Thanks for that insight Must have been something else Anyway I m out of ideas

Ian Lake · Answer

Also gt we can t just e g find and clear a backstack by some id But that s exactly what `clearBackStack ` does <https developer android com reference kotlin androidx navigation NavController clearBackStack kotlin String >

Ian Lake · Answer

So `clearBackStack ` followed by `navigate ` seems like it would do exactly what you want

Michal Klimczak · Answer

Oh this is something that we tried too but I think we need to revisit because the Shop destination is parameterised and we might have just used wrong id

Ian Lake · Answer

You have to use the exact route as your `route` when you declared your destination That exact string ` id `s and all

Michal Klimczak · Answer

Yeah because it uses hashCode on the whole route makes sense slightly smiling face

Michal Klimczak · Answer

I ll play around that