Android navigation component display multiple DialogFragments in a row

Question

Hi folks I need to throw up a series of DialogFragments one after another using the navigation component. I have encountered some pretty unusual system behavior which looks like a race condition. I show the dialogs with a global action after an item is clicked, and use the fragment result api to determine if another one should be shown.

I am using a custom layout so there's no positive / negative listeners etc., and my own continue / cancel buttons send a result back to the host fragment.

ItemsFragment.kt:

navController.navigate(RegisterItemsDirections.openModsDialog(item.id, 0))

fragment.setFragmentResultListener(ItemsFragment.MODIFIERS_REQUEST) { key, bundle ->

        //kill the current dialog
        navController.navigateUp() 
        //some logic to determine if we need another dialog...
        if(needAnotherDialog){
            //navigate to the next one
            navController.navigate(RegisterItemsDirections.openModsDialog(item.id, lastModGroupSelectionIndex + 1))
        }
    }

ModsDialogFragment.kt, when the user clicks "continue"

setFragmentResult(MODIFIERS_REQUEST, bundleOf(MODIFIERS_RESULT to selectedMods))

So the issue only appears on 3rd or more dialogs on my devices, I can see that the 1st and 2nd dialogs are completely destroyed and detached. When it displays the 3rd one, the first one attaches itself again, and appears beneath the 3rd one which I can't explain.

I've tried:

Popping the back stack in the global action's nav xml
Navigating up or dismissing the dialog fragment in the dialog itself (before calling setFragmentResult), which is the most logical place to put it
Popping the backstack instead of navigating up, basically the same thing in this case

When I don't dismiss / nav up any of the dialogs and allow them all to just stack, there's no issue. When I delay the navigation by 500ms there is no issue. So navving up and then immediately navigating to another instance of the dialog are fighting with eachother producing very strange results. What could be the solution here that doesn't involve a random delay?

Navigation version is 2.3.3 and I'm having a lot of trouble trying to update it due to AGP upgrades being incompatible with a jar I need so I'm not sure if this has been fixed.

score 0 · Answer 1 · answered Aug 16 '22 at 15:07

I figured out the issue, it's down to dumb copy pasting.

I took the donut tracker sample code and made it stack dialogs in the same way and there was no issue.

The difference between the two was I am subclassing DialogFragment and for some unknown reason doing this:

    override fun show(manager: FragmentManager, tag: String?) {

        val transaction = manager.beginTransaction()

        val prevFragment = manager.findFragmentByTag(tag)
        if (prevFragment != null) {
            transaction.remove(prevFragment)
        }
        transaction.addToBackStack(null)
        show(transaction, tag)
    }

This code predates the Nav component library I believe, and it completely f***s with the fragment manager used by the navigation component. So the moral of the story is to not do bizarre things in super classes, or better yet not super class at all.

Android navigation component display multiple DialogFragments in a row

1 Answers1