Navigation with null lists leads to indeterminate behavior [342672856]

Fixed

Bug

Status Update

No update yet.

Description

cl...@google.com

created issue #1

May 24, 2024 09:31PM

Null lists of built-in CollectionNavType such as StringListType, IntListType leads to different behavior depending on whether its string route or safe args, but either behavior seems wrong.

Take NavType.StringListType as example.

For string routes

val route = "test.com?list=null"
bundle[list] returns listOf("null")

For safe args

val route = MyRoute(null)
bundle is empty

Comments

ap...@google.com <ap...@google.com> #2May 28, 2024 02:33PM

Nested scrolling works partially (as per

http://b/122818889). Let's discuss if we need full support and if so make sure it works.

ap...@google.com <ap...@google.com> #3May 28, 2024 02:33PM

Hi!

What is 'partially' exactly?
How do I see it?
Thanks!

ap...@google.com <ap...@google.com> #4May 31, 2024 05:50PM

As of now:
- Nesting scroll views with a scroll direction perpendicular to the ViewPager2's orientation inside ViewPager2 works
- Nesting scroll views with a scroll direction parallel to the ViewPager2's orientation inside ViewPager2 does not work

cl...@google.com <cl...@google.com> #5Jun 4, 2024 12:19AM

Marked as fixed.

Horizontal ViewPager2 not correctly working into a vertical RecyclerView
Set a setNestedScrollingEnabled to the RecyclerView into the ViewPager2 (across reflection) resolves the problem

ap...@google.com <ap...@google.com> #6Jun 6, 2024 06:19PM

ageevvalentin@gmail.com, could you provide a sample app? I'd like to learn more about the circumstances that cause the problem; putting a clean ViewPager2 inside a clean RecyclerView seems to work fine, so there must be other factors involved.

pr...@google.com <pr...@google.com> #7Jun 12, 2024 10:45PM

Added a patch for androidx-master-dev that demos a horizontal ViewPager2 inside a vertical RecyclerView.

Verified that it works correctly on a:
- Nexus 4 emulator with API 17
- Nexus 5X emulator with API 28
- Pixel 2 device with API 29

To reproduce:
- Check out the Android Jetpack source (at commit 256899f482ff85cddfb050f37550be7b5ec927ef) (see steps in [1])
- Apply the patch (`git apply 0001-Add-sample-where-a-horizontal-ViewPager2-is-nested-i.patch`)
- Build and install viewpager2's integration-tests app: `./gradlew viewpager2:integration-tests:testapp:installDebug`
- Run it

Closing the issue for now, but please reopen if you have a minimal reproduction app

[1]

https://android.googlesource.com/platform/frameworks/support/+/256899f482ff85cddfb050f37550be7b5ec927ef

Issue 342672856