LazyPagingItems

operator fun get(index: Int): T?

Returns the presented item at the specified position, notifying Paging of the item access to trigger any loads necessary to fulfill prefetchDistance.

fun peek(index: Int): T?

Returns the presented item at the specified position, without notifying Paging of the item access that would normally trigger page loads.

fun refresh(): Unit

Refresh the data presented by this LazyPagingItems.

refresh triggers the creation of a new PagingData with a new instance of PagingSource to represent an updated snapshot of the backing dataset. If a RemoteMediator is set, calling refresh will also trigger a call to RemoteMediator.load with REFRESH to allow RemoteMediator to check for updates to the dataset backing PagingSource.

Note: This API is intended for UI-driven refresh signals, such as swipe-to-refresh. Invalidation due repository-layer signals, such as DB-updates, should instead use PagingSource.invalidate.

fun retry(): Unit

Retry any failed load requests that would result in a LoadState.Error update to this LazyPagingItems.

Unlike refresh, this does not invalidate PagingSource, it only retries failed loads within the same generation of PagingData.

LoadState.Error can be generated from two types of load requests:

• PagingSource.load returning PagingSource.LoadResult.Error

• RemoteMediator.load returning RemoteMediator.MediatorResult.Error

val itemCount: Int

The number of items which can be accessed.

val itemSnapshotList: ItemSnapshotList<T>

Contains the immutable ItemSnapshotList of currently presented items, including any placeholders if they are enabled. Note that similarly to peek accessing the items in a list will not trigger any loads. Use get to achieve such behavior.

val loadState: CombinedLoadStates

A CombinedLoadStates object which represents the current loading state.

fun <T : Any> LazyPagingItems<T>.itemContentType(
    contentType: ((@<Error class: unknown class> item) -> Any)? = null
): (index: Int) -> Any

Returns a factory for the content type of the item.

ContentTypes are generated with the contentType lambda that is passed in. If null is passed in, contentType of all items will default to null. If PagingConfig.enablePlaceholders is true, LazyPagingItems may return null items. Null items will automatically default to placeholder contentType.

This factory can be applied to Lazy foundations such as LazyGridScope.items or Pagers. Examples:

import androidx.compose.foundation.lazy.grid.GridCells
import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
import androidx.paging.compose.collectAsLazyPagingItems
import androidx.paging.compose.itemContentType
import androidx.paging.compose.itemKey

val lazyPagingItems = pager.collectAsLazyPagingItems()

LazyVerticalGrid(columns = GridCells.Fixed(2)) {
    items(
        count = lazyPagingItems.itemCount,
        key = lazyPagingItems.itemKey { it },
        contentType = lazyPagingItems.itemContentType { "MyPagingItems" }
    ) { index ->
        val item = lazyPagingItems[index]
        PagingItem(item = item)
    }
}

import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.material.Text
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.paging.compose.collectAsLazyPagingItems
import androidx.paging.compose.itemContentType
import androidx.paging.compose.itemKey

val lazyPagingItems = pager.collectAsLazyPagingItems()

LazyColumn {
    stickyHeader(
        key = "Header",
        contentType = "My Header",
    ) {
        Box(
            modifier = Modifier
                .padding(bottom = 10.dp)
                .background(Color.Red)
                .fillMaxWidth(),
            contentAlignment = Alignment.Center
        ) {
            Text(text = "Header", fontSize = 32.sp)
        }
    }
    items(
        count = lazyPagingItems.itemCount,
        key = lazyPagingItems.itemKey { it },
        contentType = lazyPagingItems.itemContentType { "MyPagingItems" }
    ) { index ->
        val item = lazyPagingItems[index]
        PagingItem(item = item)
    }
}

fun <T : Any> LazyPagingItems<T>.itemKey(
    key: ((@<Error class: unknown class> item) -> Any)? = null
): (index: Int) -> Any

Returns a factory of stable and unique keys representing the item.

Keys are generated with the key lambda that is passed in. If null is passed in, keys will default to a placeholder key. If PagingConfig.enablePlaceholders is true, LazyPagingItems may return null items. Null items will also automatically default to a placeholder key.

This factory can be applied to Lazy foundations such as LazyGridScope.items or Pagers. Examples:

import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.pager.HorizontalPager
import androidx.compose.foundation.pager.PageSize
import androidx.compose.foundation.pager.rememberPagerState
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import androidx.paging.Pager
import androidx.paging.compose.collectAsLazyPagingItems
import androidx.paging.compose.itemKey

val lazyPagingItems = pager.collectAsLazyPagingItems()
val pagerState = rememberPagerState { lazyPagingItems.itemCount }

HorizontalPager(
    modifier = Modifier.fillMaxSize(),
    state = pagerState,
    pageSize = PageSize.Fixed(200.dp),
    key = lazyPagingItems.itemKey { it }
) { index ->
    val item = lazyPagingItems[index]
    PagingItem(item = item)
}

import androidx.compose.foundation.lazy.grid.GridCells
import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
import androidx.paging.compose.collectAsLazyPagingItems
import androidx.paging.compose.itemContentType
import androidx.paging.compose.itemKey

val lazyPagingItems = pager.collectAsLazyPagingItems()

LazyVerticalGrid(columns = GridCells.Fixed(2)) {
    items(
        count = lazyPagingItems.itemCount,
        key = lazyPagingItems.itemKey { it },
        contentType = lazyPagingItems.itemContentType { "MyPagingItems" }
    ) { index ->
        val item = lazyPagingItems[index]
        PagingItem(item = item)
    }
}