Overview

Callback for PageKeyedDataSource PageKeyedDataSource.loadBefore(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback) and PageKeyedDataSource.loadAfter(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback) to return data.

A callback can be called only once, and will throw if called again.

It is always valid for a DataSource loading method that takes a callback to stash the callback and call it later. This enables DataSources to be fully asynchronous, and to handle temporary, recoverable error states (such as a network error that can be retried).

Summary

Constructors

Methods

Called to pass loaded data from a DataSource.

Call this method from your PageKeyedDataSource's PageKeyedDataSource.loadBefore(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback) and PageKeyedDataSource.loadAfter(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback) methods to return data.

It is always valid to pass a different amount of data than what is requested. Pass an empty list if there is no more data to load.

Pass the key for the subsequent page to load to adjacentPageKey. For example, if you've loaded a page in PageKeyedDataSource.loadBefore(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback), pass the key for the previous page, or null if the loaded page is the first. If in PageKeyedDataSource.loadAfter(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback), pass the key for the next page, or null if the loaded page is the last.

Parameters:

data: List of items loaded from the PageKeyedDataSource.
adjacentPageKey: Key for subsequent page load (previous page in PageKeyedDataSource.loadBefore(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback) / next page in PageKeyedDataSource.loadAfter(PageKeyedDataSource.LoadParams, PageKeyedDataSource.LoadCallback)), or null if there are no more pages to load in the current load direction.