Status Update
No update yet.
Comments
ap...@google.com
So there does seem to be a bug in Navigation that causes this to fail.
When it navigates with popUpTo and removes SecondFragment, that removal in fragment is set for a frame later and before it is actually removed the navigate call in the onViewCreated of SecondFragment enqueues another call to add it back. But we still need to destroy SecondDetailFragment which ends up marking the NavBackStackEntry associated with SecondFragment as complete before navigation has received the call from the fragment that it has been added back. So by the time it hits this check, the SecondFragment is in the correct state, but Navigation has no way of referencing it so it assumes that it is not associated with an entry.
But this is not the way this type of situation should be implemented. Instead of having the destinations as part of the NavGraph, they should:
- be managed by the childFragmentManager of
SecondFragment. So instead of going back toSecondFragmentjust to go somewhere else, each of the fragments take the entire content ofSecondFragmentand are swapped out. - for some sort of a/b testing, set different graphs in the Activity. The graphs would keep the same
SecondFragmentid, but swap out the names and then you choose the correct graph based on the condition.
Description
Version used: 1.0.0-alpha06
Navigation has the ability to set a default graph from your manifest via NavController.setMetadataGraph() and NavInflater.inflateMetadataGraph().
The existence of this API promotes bad patterns (automatic defaults that reside far from the code invoking it) and can outright break other functionality such as setting a programmatically inflated NavGraph onto a NavHostFragment (as NavHostFragment will use the metadata graph by default, calling setGraph with the wrong graph).
These API should be removed entirely to prevent issues - developers should call NavHostFragment.create() or call setGraph() with exactly the graph they want.