Navigation crashes when navigating from the initial fragment of the included graph when popUpTo is used and the destination is another included (and nested graph). [243778589]

Fixed

Bug

Status Update

No update yet.

Description

kr...@gmail.com

created issue #1

Aug 25, 2022 02:57PM

Component used: Navigation
Version used: every version since 2.4.0 (latest tested version is 2.5.1)
Latest version working correctly: 2.3.5
Devices/Android versions reproduced on: Emulator API 30, Oppo CPH2251 API 30, Samsung Galaxy S21 API 31

Repro steps:
1. Define the following 3 graphs (sample project is attached to this bug report):

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="

http://schemas.android.com/apk/res/android"
xmlns:app="

http://schemas.android.com/apk/res-auto"
xmlns:tools="

http://schemas.android.com/tools"
android:id="@+id/level_0_graph"
app:startDestination="@id/level_0_fragment">

<fragment
android:id="@+id/level_0_fragment"
android:name="com.example.nestedpopupto.Level0Fragment"
tools:layout="@layout/fragment_level_0">

<action
android:id="@+id/to_level_1"
app:popUpTo="@id/level_0_graph"
app:destination="@id/level_1" />
</fragment>

<navigation
android:id="@+id/level_1"
app:startDestination="@id/level_1_graph">

<include app:graph="@navigation/level_1_graph" />
</navigation>

</navigation>

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="

http://schemas.android.com/apk/res/android"
xmlns:app="

http://schemas.android.com/apk/res-auto"
xmlns:tools="

http://schemas.android.com/tools"
android:id="@+id/level_1_graph"
app:startDestination="@id/level_1_fragment">

<fragment
android:id="@+id/level_1_fragment"
android:name="com.example.nestedpopupto.Level1Fragment"
tools:layout="@layout/fragment_level_1">

<action
android:id="@+id/to_level_2"
app:popUpTo="@id/level_1_graph"
app:destination="@id/level_2" />
</fragment>

<navigation
android:id="@+id/level_2"
app:startDestination="@id/level_2_graph">

<include app:graph="@navigation/level_2_graph" />
</navigation>

</navigation>

<navigation xmlns:android="

http://schemas.android.com/apk/res/android"
xmlns:app="

http://schemas.android.com/apk/res-auto"
xmlns:tools="

http://schemas.android.com/tools"
android:id="@+id/level_2_graph"
app:startDestination="@id/level_2_fragment">

<fragment
android:id="@+id/level_2_fragment"
android:name="com.example.nestedpopupto.Level2Fragment"
tools:layout="@layout/fragment_level_2">
</fragment>

</navigation>

2. Use "to_level_1" to navigate to nested graph.
3. Use "to_level_2" action.

Result:
The action "to_level_2" will fail with the following stacktrace:

java.lang.IllegalArgumentException: No destination with ID 2131230965 is on the NavController's back stack. The current destination is Destination(com.example.nestedpopupto:id/level_2_fragment) class=com.example.nestedpopupto.Level2Fragment
at androidx.navigation.NavController.getBackStackEntry(NavController.kt:2209)
at androidx.navigation.NavController.addEntryToBackStack(NavController.kt:1918)
at androidx.navigation.NavController.addEntryToBackStack$default(NavController.kt:1813)
at androidx.navigation.NavController$navigate$4.invoke(NavController.kt:1721)
at androidx.navigation.NavController$navigate$4.invoke(NavController.kt:1719)
at androidx.navigation.NavController$NavControllerNavigatorState.push(NavController.kt:287)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.kt:246)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.kt:162)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.kt:83)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.kt:49)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.kt:83)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.kt:49)
at androidx.navigation.NavController.navigateInternal(NavController.kt:260)
at androidx.navigation.NavController.navigate(NavController.kt:1719)
at androidx.navigation.NavController.navigate(NavController.kt:1545)
at androidx.navigation.NavController.navigate(NavController.kt:1472)
at androidx.navigation.NavController.navigate(NavController.kt:1930)
at com.example.nestedpopupto.Level1Fragment.onViewCreated$lambda-0(Level1Fragment.kt:13)

The crash will NOT occur if any of the following is applied:
- the "to_level_2" action does not use "popUpTo"
- the "level_2_graph" is not wrapped with the <navigation>.

As one can see the "to_level_1" action is identical to the "to_level_2" action and is defined in an identical graph and it works correctly. It seems that the bug occurs only when navigation is performed in the graph that is included in an other graph.

In the end I would like to remind that everything works correctly with version 2.3.5 of the androidx.navigation.

nested-popupto.7z

22 KB

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Comments

jb...@google.com <jb...@google.com> #2Aug 25, 2022 07:38PM

Status: Won't Fix (Intended Behavior)

Nested scrolling works partially (as per

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

kr...@gmail.com <kr...@gmail.com> #3Aug 26, 2022 08:14AM

Hi!

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

kr...@gmail.com <kr...@gmail.com> #4Aug 26, 2022 08:19AM

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

kr...@gmail.com <kr...@gmail.com> #5Aug 26, 2022 08:31AM

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

kr...@gmail.com <kr...@gmail.com> #6Aug 26, 2022 09:06AM

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.

jb...@google.com <jb...@google.com> #7Aug 26, 2022 05:47PM

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

kr...@gmail.com <kr...@gmail.com> #8Aug 29, 2022 11:05AM

Re-opening as requested by a few users. Narrowed down the focus to nested scrolling elements with the same scroll direction.

jb...@google.com <jb...@google.com> Aug 30, 2022 02:30AM

Status: Assigned (reopened)

ap...@google.com <ap...@google.com> #9Aug 30, 2022 03:53PM

Any progress on this? (only talking about the "same scroll direction" issue)

I searched a lot for workarounds on Google and SO, but it seems no one really found a suitable solution yet.
The thing is that all other VerticalViewPagers out there have other problems that are similarly annoying. Most of them revolve around touch issues like "What's a click and what's a swipe" or "what's the fling threshold to snap to the next page".

So if someone knows of a working sample of VerticalViewPagers, I'd be happy to see a link :)

jb...@google.com <jb...@google.com> #10Aug 30, 2022 04:55PM

Marked as fixed.

Hi, we're unlikely to address the "same scroll direction" issue before 1.0-Stable as it's likely going to require API changes (so v1.1+).

One possible option for VerticalViewPager with nested scrolling in the same scroll direction is using a RecyclerView implementing NestedScrollingParent + PagerSnapHelper to get snapping.
You'd then have to implement the NestedScrollingParent/Child contract between parent/child RecyclerView instances.

kr...@gmail.com <kr...@gmail.com> #11Sep 1, 2022 07:47AM

Cool, thanks for this quick answer - Both pieces of information are highly appreciated (rough estimate of tackling this as well as giving hint on how to do it).
I will try implementing what you suggested and in case it is readable code, I will post it here as sample project or somthing similar.

na...@google.com <na...@google.com> #12Sep 12, 2022 05:52PM

That'd be great, much appreciated!

Issue 243778589

Description

Issue summary

Comments

jb...@google.com <jb...@google.com> #2Aug 25, 2022 07:38PM

kr...@gmail.com <kr...@gmail.com> #3Aug 26, 2022 08:14AM

kr...@gmail.com <kr...@gmail.com> #4Aug 26, 2022 08:19AM

kr...@gmail.com <kr...@gmail.com> #5Aug 26, 2022 08:31AM

kr...@gmail.com <kr...@gmail.com> #6Aug 26, 2022 09:06AM

jb...@google.com <jb...@google.com> #7Aug 26, 2022 05:47PM

kr...@gmail.com <kr...@gmail.com> #8Aug 29, 2022 11:05AM

jb...@google.com <jb...@google.com> Aug 30, 2022 02:30AM

ap...@google.com <ap...@google.com> #9Aug 30, 2022 03:53PM

jb...@google.com <jb...@google.com> #10Aug 30, 2022 04:55PM

kr...@gmail.com <kr...@gmail.com> #11Sep 1, 2022 07:47AM

na...@google.com <na...@google.com> #12Sep 12, 2022 05:52PM

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