IssueTracker

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.