Hello! Anyone knows if it's possible to use Scaffold with a BottomNavigation only on certain screens...

# compose

[Lucas Reis]

Hello! Anyone knows if it's possible to use Scaffold with a BottomNavigation only on certain screens using navigation graphs (loginGraph, mainGraph, etc using nested navigation), I know that we can't use Composables on NavHost() but there is another way?

In this way we can encapsulate the Scaffold only on parts of the app that needs BottomNavigation and we can control this state separately

[Felix Schütz]

Related to https://github.com/google/accompanist/issues/729. Unfortunately, the issue was auto-closed.

[Lucas Reis]

Nice, I'll try to add some interest on the issue.

How did you solve this problem with two NavHosts()?

[Felix Schütz]

In the case of the example app shown in the issue, I used an upper and a lower NavHost. The upper NavHost contains two routes: details and lower. The lower NavHost also contains two routes: gallery and folders. Each NavHost gets its own NavController. The lower route contains a Scaffold wrapping the lower NavHost. Then I can use the lower NavController for interactions with the scaffold and the upper NavHost when navigating to details and back.

[Felix Schütz]

This is a solution, but gets pretty messy with more screens, so a alternative solution would be great. Especially using different `NavController`s for different navigations is pretty bad imo.

[Lucas Reis]

yeah, how do you manage to navigate to the lower NavHost from the upper?

[Lucas Reis]

and can you share your NavGraph with the two NavHosts?
I didn't find an example on the docs for this situation

[Felix Schütz]

As far as I'm concerned, you can't share you NavGraph, so you need to NavControllers.

[Lucas Reis]

sorry, I was not clear hehe I meant, can you share your Navigation code?

[Felix Schütz]

To navigate to the lower NavHost, I do something like upperNavController.navigate("lower") or upperNavController.popBackStack(). In my use case, this is enough, but further navigation in the lower nav controller might be required.

[Felix Schütz]

Sorry, I don't quite understand what code you mean. For me, there were no code duplications.

[Lucas Reis]

Sorry, I mean, can you share your Navigation code, I didn't find an example on the Android docs with two NavHost()

[Lucas Reis]

Thank you for the explanation on how to navigate between upper and lower 🙂

[Felix Schütz]

Oh, sorry. Yeah, there is no example, since having two NavHosts is considered bad 😄 I don't have the code for the sample app anymore, so I can't share it right now.

[Ian Lake]

Is there a reason you aren't using the visibleEntries property on NavController to coordinate the showing/hiding of your bottom nav based on what destination you're on? That's exact the use case we describe at https://github.com/google/accompanist/issues/633#issuecomment-942988181

[Ian Lake]

We just talked about this yesterday, FWIW: https://kotlinlang.slack.com/archives/CJLTWPH7S/p1635374249413600

[Felix Schütz]

I read that thread too. This feature is very nice, but does not cover all use cases imo, e.g. for animating the incoming screen with a higher z-index than the bottom nav bar.

[Lucas Reis]

Sorry @Ian Lake, I didn't mean to ask something that we already discussed, but I was only curious if we have another way to do this without animation

[Lucas Reis]

It seemed a little strange to me to have a Scaffold with BottonNav and need to hide or show depending on the current route

[Ian Lake]

Isn't that exactly what you said you want to happen? "with a BottomNavigation only on certain screens" were your exact words

[Lucas Reis]

Yes, this solves that problem, but I was curious if we could use an Scaffold only on some screens without having to put the NavHost inside a Global Scaffold, instead put an Scaffold on part of the navigation/composable()

[Lucas Reis]

Sorry for creating other thread about something related to that 😥