IssueTracker

Artifact used : Room Version used: 2.4.0-alpha05 Devices/Android versions reproduced on: Emulator

This is more of a feature request, but trying out the new multimap feature I'm having issues with LEFT JOIN queries.

Take this example from the release notes (One-to-Many relationship):

@Query("SELECT * FROM Artist JOIN Album ON Artist.id = Album.artistId")
fun getArtistAndAlbums(): Map<Artist, List<Album>>

Let's say we want all artists, regardless if they have any albums. So we change the query to use a LEFT JOIN:

@Query("SELECT * FROM Artist LEFT JOIN Album ON Artist.id = Album.artistId")
fun getArtistAndAlbums(): Map<Artist, List<Album>>

This won't work if we have an Artist without albums, if Album doesn't have any nullable fields. Because the current implementation will always try and generate an Album object.

Is it possible to let Room return an empty list of 'Albums' in that case? Or Map<Artist, List<Album>?>?

Thanks for your time!