Paging

klibs.Paging is kotlin-only lightweight paging library

See also other klibs libraries

• kdi
• kstorage
• mikro

Installation

Gradle

implementation("ru.astrainteractive.klibs:paging:<version>")
implementation(libs.klibs.paging)

Version catalogs

[versions]
klibs-paging = "<latest-version>"

[libraries]
klibs-paging = { module = "ru.astrainteractive.klibs:paging", version.ref = "klibs-paging" }

Sample

For sample see Sample directory

It contains ComposeJB RickMortyApi paging implementation with filtering

Issues with usage

If you have issues with usage of this library - take a look into sources. Almost everything documented and designed to be easy to understand

Usage

Define your own PageContext

PageContext is the description of your current page. It can contain int, string, anything. Most users describe page as Integer value, so here's example:

Factory here is used to create next or previous page context

data class LongPageContext(val page: Long) : PageContext {
    object Factory : PageContext.Factory<LongPageContext> {
        override fun next(pageContext: LongPageContext): LongPageContext {
            return pageContext.copy(page = pageContext.page + 1)
        }
    }
}

Create PagedDataSource

Mostly you will use LambdaPagedListDataSource, but it also can be created with PagedListDataSource interface

// With interface
class BytesPagedListDataSource : PagedListDataSource<Byte, LongPageContext> {
    override suspend fun getListResult(pagingState: PagingState<Byte, LongPageContext>): Result<List<Byte>> {
        return runCatching { listOf(0.toByte()) }
    }
}

// Or lambda
val bytesPagedListDataSource = LambdaPagedListDataSource<Byte, LongPageContext> {
    runCatching { listOf(0.toByte()) }
}

Define your own paging collector

For custom PageContext you need to create PagerCollector. It can be made with delegation

class LongPagerCollector<T>(
    private val initialPage: Long = 0L,
    private val pageSize: Int = 10,
    private val pager: PagedListDataSource<T, LongPageContext>,
) : PagingCollector<T, LongPageContext> by DefaultPagingCollector(
    initialPagingStateFactory = {
        PagingState(
            pageContext = LongPageContext(page = initialPage),
            items = emptyList(),
            pageSizeAtLeast = pageSize,
            isLastPage = false,
            isLoading = false,
            isFailure = false
        )
    },
    pager = pager,
    pageContextFactory = LongPageContext.Factory
)

Simple repository example

/**
 * Your custom repository implementation
 */
class MyRepositoryImpl : MyRepository {
    /**
     * Define your paging collector
     */
    private val pagingCollector = LongPagerCollector(
        initialPage = 0,
        pager = CoroutineHandledPagedListDataSource<String, LongPageContext> { pagingState ->
            val page = pagingState.pageContext.page
            val pageSize = pagingState.pageSizeAtLeast
            if (Random.nextBoolean()) List(pagingState.pageContext.page.toInt()) { i -> "Value number ${pageSize * page} + $i" }
            else error("Some error")
        }
    )

    /**
     * Define stateflow of your pager
     */
    override val pagingState: StateFlow<PagingState<String, LongPageContext>> = pagingCollector.state

    /**
     * Add ability to reset it
     */
    override suspend fun reset() {
        pagingCollector.resetAndJoin()
    }

    /**
     * Add ability to load next page
     */
    override suspend fun loadNextPage() {
        pagingCollector.loadNextPage()
    }
}