RemoteMediator and Caching

A plain network PagingSource works, but if the connection drops the list is empty. For a robust app you want the database as the single source of truth and the network filling it in the background.

That is exactly what RemoteMediator enables: page from the local database, and fetch more from the network when the database runs out.

With RemoteMediator the data flows in one direction:

• The UI pages from a Room PagingSource
• When Room nears its end, RemoteMediator fetches the next network page
• The network result is written into Room
• Room emits the new rows, and the UI updates

The user always sees cached data instantly, even offline.