NavInflater uses obtainAttributes which doesn't resolve theme attributes [178291654]

Fixed

Bug

androidx-bug-bounty

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Description

[Deleted User]

created issue #1

Jan 24, 2021 11:37PM

Component used: Navigation Version used: 2.3.2 Devices/Android versions reproduced on: N/A

The current implementation of the nav graph inflater uses Resources::obtainAttributes, which doesn't deeply resolve theme attributes, meaning the following won't work:

// in attrs.xml
<attr name="transitionDefaultEnter" format="reference"/>
<attr name="transitionDefaultExit" format="reference"/>
<attr name="transitionDefaultPopEnter" format="reference"/>
<attr name="transitionDefaultPopExit" format="reference"/>

<attr name="transitionModalEnter" format="reference"/>
<attr name="transitionModalExit" format="reference"/>
<attr name="transitionModalPopEnter" format="reference"/>
<attr name="transitionModalPopExit" format="reference"/>

// in themes.xml
<item name="transitionDefaultEnter">@anim/slide_in_from_right</item>
<item name="transitionDefaultPopExit">@anim/slide_out_to_right</item>
...

// in nav_main.xml
<action
   android:id="@+id/someActionId"
   app:destination="@id/someDestination"
   app:enterAnim="?attr/transitionDefaultEnter"
   app:exitAnim="?attr/transitionDefaultExit"
   app:popEnterAnim="?attr/transitionDefaultPopEnter"
   app:popExitAnim="?attr/transitionDefaultPopExit" />

<action
   android:id="@+id/someOtherActionId"
   app:destination="@id/someModalScreenDestination"
   app:enterAnim="?attr/transitionModalEnter"
   app:exitAnim="?attr/transitionModalExit"
   app:popEnterAnim="?attr/transitionModalPopEnter"
   app:popExitAnim="?attr/transitionModalPopExit" />

Obviously this functionality would have a lot of use when it comes to "theming" an app's motion (and defining different "categories" of motion for an app) as well as being able to change animations more easily from one place in much the same was as changing colors or other theme attribute values.

Is there a reason the NavInflater hasn't been set up to resolve these attributes?

Comments

il...@google.com <il...@google.com> #2Jan 26, 2021 11:01PM

Assigned to jb...@google.com.

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.

ap...@google.com <ap...@google.com> #3May 21, 2021 07:34PM

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

jb...@google.com <jb...@google.com> #4May 21, 2021 07:50PM

Marked as fixed.

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.

Issue 178291654

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Comments

il...@google.com <il...@google.com> #2Jan 26, 2021 11:01PM

ap...@google.com <ap...@google.com> #3May 21, 2021 07:34PM

jb...@google.com <jb...@google.com> #4May 21, 2021 07:50PM

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