Empty list after delete last item on page [168169730]

Fixed

Bug

Status Update

No update yet.

Description

de...@gmail.com

created issue #1

Sep 10, 2020 04:06PM

Version used: 3.0.0-alpha06
Devices/Android versions reproduced on: all

Case: I have list, and I can delete items. So for example I have 21 items and pageSize = 10. So I load page0, then page1 and page2. Then I delete last item, and invalidate source, state.anchorPosition = 20 , so I started with page = 2, there are no items and I return LoadResult(emptyList, 1, null) but there are no Prepend load so I get empty state in UI.

Code snipped of PagingSource

abstract class BasePagingSource<T : Any> : PagingSource<Int, T>() {
    abstract suspend fun load(page: Int, pageSize: Int): PageLoadResult<T>

    @ExperimentalPagingApi
    override fun getRefreshKey(state: PagingState<Int, T>): Int? {
        val recentPosition = state.anchorPosition ?: 0
        val prevPages = state.pages.firstOrNull()?.prevKey?.let { (it + 1) } ?: 0
        val pageKey = recentPosition / state.config.pageSize
        return pageKey + prevPages
    }

    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, T> {
        val nextPageNumber = params.key ?: 0
        return when (val result = load(nextPageNumber, params.loadSize)) {
            is PageLoadResult.Success -> {
                LoadResult.Page(
                    getPageData(result),
                    (nextPageNumber - 1).takeIf { page -> page >= 0 },
                    (nextPageNumber + 1).takeIf { result.data.size == params.loadSize }
                )
            }
            is PageLoadResult.Fail -> LoadResult.Error(result.error.exception ?: UnknownError())
        }
    }

    protected open fun getPageData(result: PageLoadResult.Success<T>) = result.data
}

sealed class PageLoadResult<T> {
    data class Success<T>(val data: List<T>) : PageLoadResult<T>()
    data class Fail<T>(val error: Error) : PageLoadResult<T>()
}

I could not find out why there are no Prepend loading, may be I missed smth.

Comments

du...@google.com <du...@google.com> #2Sep 11, 2020 05:25AM

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

du...@google.com <du...@google.com> Oct 28, 2020 07:10AM

Accepted by du...@google.com.

ap...@google.com <ap...@google.com> #3Nov 12, 2020 01:12AM

Marked as fixed.

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

commit 9ecbc50181bdc111c856470e08acd5a676dc944e
Author: Dustin Lam <dustinlam@google.com>
Date: Thu Oct 29 20:55:37 2020

Manually trigger APPEND / PREPEND to avoid stalling on empty initial load

Add a new ViewportHint type which does not require an anchorPosition
that is de-prioritized against hints with anchorPosition to allow
PREPEND / APPEND loads to work even when there are no items loaded.

Relnote: "Presenting an empty list either due to empty initial page or
heavy filtering will no longer prevent Paging from kicking off PREPEND
or APPEND loads."
Fixes: 168169730
Test: ./gradlew paging:paging-common:test
Change-Id: I3e702b6daf002f6dd3010c9b6f8867caf95135e0

M paging/common/src/main/kotlin/androidx/paging/PageEvent.kt
M paging/common/src/main/kotlin/androidx/paging/PageFetcherSnapshot.kt
M paging/common/src/main/kotlin/androidx/paging/PageFetcherSnapshotState.kt
M paging/common/src/main/kotlin/androidx/paging/PagePresenter.kt
M paging/common/src/main/kotlin/androidx/paging/PagingDataDiffer.kt
M paging/common/src/main/kotlin/androidx/paging/TransformablePage.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/PageFetcherSnapshotStateTest.kt
M paging/common/src/test/kotlin/androidx/paging/PageFetcherSnapshotTest.kt
M paging/common/src/test/kotlin/androidx/paging/PageFetcherTest.kt
M paging/common/src/test/kotlin/androidx/paging/PagingDataDifferTest.kt
M paging/common/src/test/kotlin/androidx/paging/SeparatorsTest.kt

https://android-review.googlesource.com/1481063

Issue 168169730

Description

Issue summary

Comments

du...@google.com <du...@google.com> #2Sep 11, 2020 05:25AM

du...@google.com <du...@google.com> Oct 28, 2020 07:10AM

ap...@google.com <ap...@google.com> #3Nov 12, 2020 01:12AM

Add comment

Issue metadata