public abstract class RxPagingSource<Key extends Object, Value extends Object> extends PagingSource

   ↳ PagingSource
     ↳ RxPagingSource

Rx-based compatibility wrapper around PagingSource's suspending APIs.

 * Sample RxPagingSource which loads `Item`s from network requests via Retrofit to a backend
 * service, which uses String tokens to load pages (each response has a next/previous token).
class MyPagingSource(
    val myBackend: RxBackendService,
    val searchTerm: String
) : RxPagingSource<String, Item>() {
    override fun loadSingle(params: LoadParams<String>): Single<LoadResult<String, Item>> {
        return myBackend
            // Single-based network load
            .searchUsers(searchTerm, params.key)
            .map<LoadResult<String, Item>> { result ->
                    data = result.items,
                    prevKey = result.prev,
                    nextKey = result.next
            .onErrorReturn { e ->
                when (e) {
                    // Retrofit calls that return the body type throw either IOException for
                    // network failures, or HttpException for any non-2xx HTTP status codes.
                    // This code reports all errors to the UI, but you can inspect/wrap the
                    // exceptions to provide more context.
                    is IOException -> LoadResult.Error(e)
                    is HttpException -> LoadResult.Error(e)
                    else -> throw e

    override fun getRefreshKey(state: PagingState<String, Item>): String? {
        return state.anchorPosition?.let { state.closestItemToPosition(it)?.id }


Public constructors

<Key extends Object, Value extends Object> RxPagingSource()

Public methods

final @NonNull PagingSource.LoadResult<@NonNull Key, @NonNull Value>

Loading API for PagingSource.

abstract @NonNull Single<@NonNull PagingSource.LoadResult<@NonNull Key, @NonNull Value>>

Loading API for PagingSource.

Inherited methods

From class PagingSource
abstract Key
getRefreshKey(PagingState<Key, Value> state)

Provide a Key used for the initial load for the next PagingSource due to invalidation of this PagingSource.

final void

Signal the PagingSource to stop loading.

final void
registerInvalidatedCallback(Function0<Unit> onInvalidatedCallback)

Add a callback to invoke when the PagingSource is first invalidated.

final void
unregisterInvalidatedCallback(Function0<Unit> onInvalidatedCallback)

Remove a previously added invalidate callback.

Public constructors


public final <Key extends Object, Value extends Object> RxPagingSource()

Public methods