RxRemoteMediator

public abstract class RxRemoteMediator<Key extends Object, Value extends Object> extends RemoteMediator

Object
   ↳ RemoteMediator
     ↳ RxRemoteMediator

RxJava2 compatibility wrapper around RemoteMediator's suspending APIs.

Summary

Public constructors

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

Public methods

final @NonNull RemoteMediator.InitializeAction

Callback fired during initialization of a PagingData stream, before initial load.

@NonNull Single<@NonNull RemoteMediator.InitializeAction>

Callback fired during initialization of a PagingData stream, before initial load.

final @NonNull RemoteMediator.MediatorResult
load(
    @NonNull LoadType loadType,
    @NonNull PagingState<@NonNull Key, @NonNull Value> state
)

Callback triggered when Paging needs to request more data from a remote source due to any of the following events:

abstract @NonNull Single<@NonNull RemoteMediator.MediatorResult>
loadSingle(
    @NonNull LoadType loadType,
    @NonNull PagingState<@NonNull Key, @NonNull Value> state
)

Implement this method to load additional remote data, which will then be stored for the PagingSource to access.

Public constructors

RxRemoteMediator

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

Public methods

initialize

@NonNull
public final RemoteMediator.InitializeAction initialize()

Callback fired during initialization of a PagingData stream, before initial load.

This function runs to completion before any loading is performed.

Returns
RemoteMediator.InitializeAction

InitializeAction used to control whether load with load type REFRESH will be immediately dispatched when the first PagingData is submitted:

initializeSingle

@NonNull
public Single<@NonNull RemoteMediator.InitializeActioninitializeSingle()

Callback fired during initialization of a PagingData stream, before initial load.

This function runs to completion before any loading is performed.

Returns
Single<@NonNull RemoteMediator.InitializeAction>

InitializeAction indicating the action to take after initialization:

load

@NonNull
public final RemoteMediator.MediatorResult load(
    @NonNull LoadType loadType,
    @NonNull PagingState<@NonNull Key, @NonNull Value> state
)

Callback triggered when Paging needs to request more data from a remote source due to any of the following events:

It is the responsibility of this method to update the backing dataset and trigger PagingSource.invalidate to allow androidx.paging.PagingDataAdapter to pick up new items found by load.

The runtime and result of this method defines the remote LoadState behavior sent to the UI via CombinedLoadStates.

This method is never called concurrently unlessPager.flow has multiple collectors. Note that Paging might cancel calls to this function if it is currently executing a PREPEND or APPEND and a REFRESH is requested. In that case, REFRESH has higher priority and will be executed after the previous call is cancelled. If the load call with REFRESH returns an error, Paging will call load with the previously cancelled APPEND or PREPEND request. If REFRESH succeeds, it won't make the APPEND or PREPEND requests unless they are necessary again after the REFRESH is applied to the UI.

Parameters
@NonNull LoadType loadType

LoadType of the condition which triggered this callback.

@NonNull PagingState<@NonNull Key, @NonNull Value> state

A copy of the state including the list of pages currently held in memory of the currently presented PagingData at the time of starting the load. E.g. for load(loadType = APPEND), you can use the page or item at the end as input for what to load from the network.

Returns
RemoteMediator.MediatorResult

MediatorResult signifying what LoadState to be passed to the UI, and whether there's more data available.

loadSingle

@NonNull
public abstract Single<@NonNull RemoteMediator.MediatorResultloadSingle(
    @NonNull LoadType loadType,
    @NonNull PagingState<@NonNull Key, @NonNull Value> state
)

Implement this method to load additional remote data, which will then be stored for the PagingSource to access. These loads take one of two forms:

  • type == LoadType.PREPEND / LoadType.APPEND The PagingSource has loaded a 'boundary' page, with a null adjacent key. This means this method should load additional remote data to append / prepend as appropriate, and store it locally.

  • type == LoadType.REFRESH The app (or initialize) has requested a remote refresh of data. This means the method should generally load remote data, and replace all local data.

The runtime of this method defines loading state behavior in boundary conditions, which affects e.g., LoadState callbacks registered to androidx.paging.PagingDataAdapter.

NOTE: A PagingSource.load request which is fulfilled by a page that hits a boundary condition in either direction will trigger this callback with LoadType.PREPEND or LoadType.APPEND or both. LoadType.REFRESH occurs as a result of initialize.

Parameters
@NonNull LoadType loadType

LoadType of the boundary condition which triggered this callback.

@NonNull PagingState<@NonNull Key, @NonNull Value> state

A copy of the state including the list of pages currently held in memory of the currently presented PagingData at the time of starting the load. E.g. for load(loadType = END), you can use the page or item at the end as input for what to load from the network.

Returns
Single<@NonNull RemoteMediator.MediatorResult>

MediatorResult signifying what LoadState to be passed to the UI, and whether there's more data available.