After 2.6.0-alpha05 navigating re-adds root nav graph entry to back stack [275407804]

Fixed

Bug

Status Update

No update yet.

Description

ra...@gmail.com

created issue #1

Mar 28, 2023 09:59AM

Component used: Navigation

Version used: 2.6.0-alpha05

Devices/Android versions reproduced on:

Not relevant, it will happen on all.

If this is a bug in the library, we would appreciate it if you could attach: Sample project to trigger the issue.

I'll add a couple of simple kotlin files instead, just use them with any version after 2.6.0-alpha05 navigation dependency and you'll be able to reproduce it.

MainActivity_rook.kt File

If we add destinations directly on "root" (route passed to NavHost call), then this will be the log of the back stack as we navigate:

stack = []
stack = [root, home]
stack = [root, home, root, screen_two/{id}]
stack = [root, home, root, screen_two/{id}, root, screen_three]

MainActivity_no_root.kt File

If we add a navigation graph ("home_graph") as the only direct child of "root" and add destinations on that instead, it will work as expected, we'll see this:

stack = []
stack = [root, home_graph, home]
stack = [root, home_graph, home, screen_two/{id}]
stack = [root, home_graph, home, screen_two/{id}, screen_three]

This was a breaking change that could introduce bugs for anyone relying on that "root" sent on the NavHost and popping up to that, since after updating navigation it would instead just pop their last screen.

MainActivity_no_root.kt

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MainActivity_root.kt

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Comments

ra...@gmail.com <ra...@gmail.com> #2Mar 28, 2023 10:11AM

Oh I forgot to mention that I thought it might be connected to this issue: https://issuetracker.google.com/issues/243778589. But after trying 2.5.2 I can say that the issue persists.

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jb...@google.com <jb...@google.com> Mar 28, 2023 04:08PM

Assigned to cl...@google.com.

cl...@google.com <cl...@google.com> #3Mar 30, 2023 09:46PM

Please provide a minimal sample project along with the minimal steps to recreate the issue in the project.

Message last modified on Mar 30, 2023 10:01PM

ap...@google.com <ap...@google.com> #4Mar 30, 2023 11:11PM

Sorry for the delay. I got a working example here: https://github.com/Del-S/issues. The project is set up to crash when navigating to ThirdFragment (nested nav graph) with poping the graph.

I poked into it a little bit and it seems to be connected to SafeArgs gradle plugin. When safe args is used to navigate to ThirdFragment (with nested graph poped) it will try to recreate te parent but there were no arguments passed so it crashes.

Steps to reproduce:

Navigate from Second Fragment to Child nav graph (with non-nullable parameters).
Navigate to Third fragment using SafeArgs and the app crashes.

Crash log:

Process: cz.dels.issues, PID: 1743
java.lang.NullPointerException: null cannot be cast to non-null type kotlin.Long
at androidx.navigation.NavType$Companion$LongType$1.get(NavType.kt:352)
at androidx.navigation.NavType$Companion$LongType$1.get(NavType.kt:342)
at androidx.navigation.NavArgument.verify(NavArgument.kt:76)
at androidx.navigation.NavDestination.addInDefaultArgs(NavDestination.kt:502)
at androidx.navigation.NavController.addEntryToBackStack(NavController.kt:1865)
at androidx.navigation.NavController.addEntryToBackStack$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.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 cz.dels.issues.SecondFragment.onViewCreated$lambda-0(SecondFragment.kt:38)
at cz.dels.issues.SecondFragment.$r8$lambda$XDYnOS_cYrafiNQ5rcCu1WCn0IE(Unknown Source:0)
at cz.dels.issues.SecondFragment$$ExternalSyntheticLambda0.onClick(Unknown Source:2)

Note: If in step 2 SaveArgs is not used then navigation works correctly. More information is here: https://github.com/Del-S/issues/blob/master/app/src/main/java/cz/dels/issues/SecondFragment.kt#L37.

cl...@google.com <cl...@google.com> #5Mar 30, 2023 11:36PM

Marked as fixed.

Ups a typo: Navigate from ~~Second~~ First Fragment to Child nav graph (with non-nullable parameters).

Note: sorry for the spam but I am not able to edit my own comment.

na...@google.com <na...@google.com> #6Apr 5, 2023 06:27PM

This has been fixed and will be available in navigation 2.6.0-alpha08

ra...@gmail.com <ra...@gmail.com> #7Apr 5, 2023 09:13PM

Project: platform/frameworks/support
Branch: androidx-main

commit 6b358154b794a0456b089ac8e548bfb830dd6c22
Author: Clara Fok <clarafok@google.com>
Date: Tue Mar 14 17:56:12 2023

Fix missing non-nullable arg when rebuilding hierarchy

When navigating with NavDirections, args is populated with an empty bundle. This causes issue when we rebuild parent hierarchy while adding a new entry to NavBackStack. If the Entry being rebuilt contains a non-nullalbe arg, i.e. Long, this empty bundle will cause an exception.

Test: ./gradlew navigation:navigation-runtime:cC
Bug: 249988437
Change-Id: I5c8ce739ad9a3428c8a8de13eae391bfff0db5df

M navigation/navigation-runtime/src/androidTest/java/androidx/navigation/NavControllerTest.kt
M navigation/navigation-runtime/src/main/java/androidx/navigation/NavController.kt

https://android-review.googlesource.com/2488855

Issue 275407804

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Comments

ra...@gmail.com <ra...@gmail.com> #2Mar 28, 2023 10:11AM

jb...@google.com <jb...@google.com> Mar 28, 2023 04:08PM

cl...@google.com <cl...@google.com> #3Mar 30, 2023 09:46PM

ap...@google.com <ap...@google.com> #4Mar 30, 2023 11:11PM

cl...@google.com <cl...@google.com> #5Mar 30, 2023 11:36PM

na...@google.com <na...@google.com> #6Apr 5, 2023 06:27PM

ra...@gmail.com <ra...@gmail.com> #7Apr 5, 2023 09:13PM

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