Application get crashed when reached at end of List. [158892717]

Fixed

Bug

Status Update

No update yet.

Description

th...@gmail.com

created issue #1

Jun 14, 2020 08:05AM

Component used: Paging
Version used: 3.0.0-alpha01

I have followed codelabs paging 3 tutorial. I have implemented paging from network and database.
This is the repository provided by codelabs tutorial :-

https://github.com/googlecodelabs/android-paging

I have founded 2 issues in Paging 3.

1. Application get crashed when Recylerview reach at end(last page).
Inside GithubRemoteMediator.kt
I have set val endOfPaginationReached = page > 2 to allow maximum 2 pages for testing.
So, the problem is when I reach at the last page of list, application get crashed as remoteKeys.nextKey is null(as we have set nextKey=null for last page of list).

2. Offline cache broken
How to support caching when application is open without internet connection. currently it is showing retry button. How to show previously loaded data. I have tried to fix this by removing

// clear all tables in the database
if (loadType == LoadType.REFRESH) {
repoDatabase.remoteKeysDao().clearRemoteKeys()
repoDatabase.reposDao().clearRepos()
}

as this will now not gone delete data from database.
But still Pager does not load data available.

So how I can fix this problem?
Is there any way of detecting end of paging?
Why Pager is not returning data available in database.

Comments

du...@google.com <du...@google.com> #2Jun 15, 2020 04:16PM

Reassigned to du...@google.com.

Project: platform/frameworks/support
Branch: androidx-master-dev

commit c60f33e229e31ab328ef6b59dab63b264954831c
Author: Alexandre Elias <aelias@google.com>
Date: Fri Jul 10 16:23:09 2020

Semantics no-op cleanups

Partly in response to lmr's broad code review, I did a pass of
superficial API/implementation cleanup. The main changes are:

- I changed each Boolean SemanticsProperty where false is equivalent to
not being present to take "Unit" instead. This is conceptually
clearer: it avoids questions like "can I cancel out a semantics from a
merged child by setting it to false?" Because "property = Unit" looks
weird, I also changed the style of these to "property()".

- I moved the Semantics id generator closer to where it's used, in
SemanticsModifierCore. I made it internal and an AtomicInt.
(Note that integer ids are heavily used in the Android
AccessibilityNodeInfo APIs so I can't simply remove them entirely.)

- I deleted dead code. Some examples include SemanticsHintOverrides,
a public API not connected to anything, and SemanticsPropertyKey
merge() open method which is never called. (In both cases I have
a different plan in mind for accessibility.)

Fixes: 145951226
Fixes: 145955412
Test: existing tests
Relnote: "Single-value semantics properties now use a calling style.
For example, 'semantics { hidden = true }' is now written as:
'semantics { hidden() }'."

Change-Id: Ic1afd12ea22c926babc9662f1804d80b33aa0cfc

M ui/integration-tests/benchmark/src/androidTest/java/androidx/ui/benchmark/test/LayoutNodeModifierBenchmark.kt
M ui/ui-core/api/0.1.0-dev15.txt
M ui/ui-core/api/current.txt
M ui/ui-core/api/public_plus_experimental_0.1.0-dev15.txt
M ui/ui-core/api/public_plus_experimental_current.txt
M ui/ui-core/api/restricted_0.1.0-dev15.txt
M ui/ui-core/api/restricted_current.txt
M ui/ui-core/src/androidAndroidTest/kotlin/androidx/ui/graphics/vector/VectorTest.kt
M ui/ui-core/src/androidAndroidTest/kotlin/androidx/ui/semantics/SemanticsTests.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidActuals.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidComposeView.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidComposeViewAccessibilityDelegateCompat.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidPopup.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/Expect.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsConfiguration.kt
D ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsHintOverrides.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsModifier.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsNode.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsOwner.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsWrapper.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/semantics/SemanticsProperties.kt
M ui/ui-foundation/api/0.1.0-dev15.txt
M ui/ui-foundation/api/current.txt
M ui/ui-foundation/api/public_plus_experimental_0.1.0-dev15.txt
M ui/ui-foundation/api/public_plus_experimental_current.txt
M ui/ui-foundation/api/restricted_0.1.0-dev15.txt
M ui/ui-foundation/api/restricted_current.txt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/Clickable.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/Dialog.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/Scroller.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/selection/Selectable.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/selection/Toggleable.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/semantics/FoundationSemanticsProperties.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/ButtonTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/CardTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/CheckboxScreenshotTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/RadioButtonScreenshotTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/ScaffoldTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/SnackbarTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/SurfaceTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/ripple/RippleIndicationTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/textfield/TextFieldScreenshotTest.kt
M ui/ui-material/src/main/java/androidx/ui/material/AppBar.kt
M ui/ui-material/src/main/java/androidx/ui/material/TextFieldImpl.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/AssertsTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/CallSemanticsActionTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/ErrorMessagesTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/FindersTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/PrintToStringTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/ScrollToTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/TextActionsTest.kt
M ui/ui-test/src/main/java/androidx/ui/test/Actions.kt
M ui/ui-test/src/main/java/androidx/ui/test/Filters.kt
M ui/ui-text/api/0.1.0-dev15.txt
M ui/ui-text/api/current.txt
M ui/ui-text/api/public_plus_experimental_0.1.0-dev15.txt
M ui/ui-text/api/public_plus_experimental_current.txt
M ui/ui-text/api/restricted_0.1.0-dev15.txt
M ui/ui-text/api/restricted_current.txt
M ui/ui-text/src/commonMain/kotlin/androidx/ui/text/CoreTextField.kt
M ui/ui-text/src/commonMain/kotlin/androidx/ui/text/TextSemanticsProperties.kt

https://android-review.googlesource.com/1360099

th...@gmail.com <th...@gmail.com> #3Jun 17, 2020 09:21AM

1. stack for remoteKeys.nextKey gets null

06-17 14:48:03.981 18015-18015/com.example.android.codelabs.paging E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.codelabs.paging, PID: 18015
java.io.InvalidObjectException: Remote key should not be null for APPEND
at com.example.android.codelabs.paging.data.GithubRemoteMediator.load(GithubRemoteMediator.kt:68)
at com.example.android.codelabs.paging.data.GithubRemoteMediator$load$1.invokeSuspend(GithubRemoteMediator.kt)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:7325)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

2. I have checked loadStateFlow / listener logic and changed it to listen only remote errors using loadState.mediator.refersh. But still, in offline mode application shows empty list. I have also removed the loadStateFlow / listener but still, it's not working in offline mode. It is not fetching data available in databa.

ap...@google.com <ap...@google.com> #4Jun 17, 2020 08:08PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit b5e4aa03a057d56a55ffc6abf250ce8a34e5071b
Author: Dustin Lam <dustinlam@google.com>
Date: Wed Jun 17 00:50:31 2020

Allow local REFRESH even if remote REFRESH fails

Bug: 158892717
Test: ./gradlew paging:paging-common:test
Change-Id: I38b1b1784af935cfbd8b937d9f4ab372f59619ed

M paging/common/src/main/kotlin/androidx/paging/PageFetcherSnapshot.kt
M paging/common/src/main/kotlin/androidx/paging/PagerState.kt
M paging/common/src/main/kotlin/androidx/paging/ViewportHint.kt
M paging/common/src/test/kotlin/androidx/paging/CachingTest.kt
M paging/common/src/test/kotlin/androidx/paging/PageFetcherSnapshotTest.kt
M paging/common/src/test/kotlin/androidx/paging/TestPagingSourceExt.kt
M testutils/testutils-paging/src/main/java/androidx/paging/TestPagingSource.kt

https://android-review.googlesource.com/1341068

du...@google.com <du...@google.com> #5Jun 17, 2020 08:16PM

Marked as fixed.

Re: 1. That check was built into the codelab since it doesn't expect to run out of pages to append, but since you changed the logic you'll also need to update that check here: https://github.com/googlecodelabs/android-paging/blob/step13-19_network_and_database/app/src/main/java/com/example/android/codelabs/paging/data/GithubRemoteMediator.kt#L68

You can simply replace it by returning MediatorResult.Success(endOfPaginationReached = true)

Re: 2. I ended up repro-ing this and fixing it, should be released with alpha02.

du...@google.com <du...@google.com> #6Jun 17, 2020 08:18PM

Let me know if you have trouble getting 1. to work - happy to help you figure it out, but closing this ticket out for now.

th...@gmail.com <th...@gmail.com> #7Jun 18, 2020 03:08AM

Thank you. I have fixed the 1st issue.

Issue 158892717