navigation component question: I have fragments A,...

# android

[solidogen]

navigation component question:
I have fragments A,B,C
I want to have a shortcut of going from A to C, but also have a way to popup from C to B
what is the recommended way to do this?

[Remy Benza]

create a global destination

[solidogen]

do you mean global action C->B?

[Remy Benza]

no, with a global action you can navigate to any destination from any fragment

[solidogen]

I’m not sure how this helps me

[Remy Benza]

you want to go from A to C, but also from C to B?

[solidogen]

I want to go A to C (skipping B) while keeping B in the backstack so I can go back to B when backpressed

[solidogen]

I tried action C -> B with popup but it doesn’t seem to do anything

[Remy Benza]

ok so when you're on fragment A, just call if(conditional nav is true)
findnavcontroller.navigate(to B) and also findnavcontroller.navigate(to C). You will end up on C with B on the back stack

[Remy Benza]

override the animation toB

[Remy Benza]

so it's not visible to the user

[Remy Benza]

I think there is also an manuel way off adding fragments to the backstack with a navcontroller

[Remy Benza]

check the docs, never needed it

[solidogen]

thanks for help, I’ll try

[Remy Benza]

If this does not work well UI wise, you could also override onBackPressed() in your activity, and place your logic there

[solidogen]

I do, but my action doesn’t work, probably because there is no fragment B on the backstack

[Remy Benza]

override fun onBackPressed() {
    val navController = findNavController(R.id.nav_host_fragment)
    if (navController.currentDestination?.id == fragment C) {

[Remy Benza]

that's when a global destination comes in hand

[solidogen]

I use

requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner) { navigator.goBack() }

in the fragment

[Remy Benza]

check with debugger the current backstack

[Remy Benza]

https://developer.android.com/reference/androidx/navigation/NavController#getPreviousBackStackEntry()

[solidogen]

I/NavController: Ignoring popBackStack to destination <http://com.xxx.xxx:id/b_fragment|com.xxx.xxx:id/b_fragment> as it was not found on the current back stack

[Remy Benza]

instead of calling .popBackStack when on fragment C

[Remy Benza]

just call navigate to B

[Remy Benza]

inside onBackPress in your activity

[Remy Benza]

or your fragment with the dispatcher you showed

[solidogen]

this feels hacky, I think I could use a deep link? no real samples of this anywhere

[solidogen]

but I see I can set a destination inside a deep link

[Remy Benza]

why hacky? you go from A to C, but then want to magically go to B when pressing back

[Remy Benza]

you need to override the default behavior in that case, because going back would mean go to A

[Remy Benza]

so you override onbackpressed in your hosting activity

[Remy Benza]

I usually tie a viewmodel to the activity lifecycle which I use to communicate from the fragment to the activity

[Remy Benza]

so when you're on C, the user performs the action to go to B, set a boolean value in the viewmodel to true, and read this boolean inside onbackPressed in the activity

[Remy Benza]

if it's true, than apply the going to B route, if it's false then just call super.Onbackpressed

[Remy Benza]

easiest option, can also be done with SafeArgs

[Remy Benza]

but that involves bundles and keys

[solidogen]

overriding onbackpressed this way and making a cascade if-elses will cripple maintainability

[solidogen]

ideally I would like to navigate and set backstack fragments myself

[Remy Benza]

try the first option I gave you

[Remy Benza]

navigating twice

[Remy Benza]

if that doesnt work UI wise, this is an alternative

[Remy Benza]

you decide what's best for your codebase

[Remy Benza]

goodluck!

[solidogen]

I have a long registration flow, so I may end up doing 10 navigates A-B-C-D-E-F-G-H-I-J

[solidogen]

I feel this will break fast

[Remy Benza]

option 2 then 😉

[solidogen]

thanks for discussion