I am using Dropbox Store4 (which is something like a NetworkBoundResource). I am experiencing an issue where my Fetcher is never called because my reader returns a non-null empty list (Store sees this as valid data). How can I adjust my Room DAO to return null if there are no results (so I can successfully trigger Fetch to actually load new data?). See thread for screenshots

What about not using your Dao directly? Can you put some kind of wrapper around it that checks if the list isEmpty and if true, returns null else the list?

I tried out

showDao.loadHomeScreen(now).onEmpty { emit(null ) }

with no success

can you confirm that onEmpty is called? i think the flow might still emit the empty list and onEmpty is never called

Welp, I tried out a breakpoint and manually logging but it doesn't seem to get called

yes, thats why you need to remove the onEmpty callback and put your dao inside something like ShowLocalDataSource(val showDao: ShowDao) { loadHomeScreen() : List<...> { val shows = showDao.loadHomeScreen() return if (shows.isEmpty()) { null else { shows } } }

It works when using List directly but I need to use Flow/LiveData to constantly observe database changes

try creating a new flow inside your localdatasource of Flow<List<>?> and then call flow {} in which you decide to emit(shows) or emit(null)

that works thank you very much! Still wish

onEmpty

worked because this is quite some lines of code to achieve something simple

thats true, great it works. maybe you can shorten this somehow or just include it directly in your store thing but this could get quite messy