Hm, tried experimenting with soup views but wasn't finding the results I want...

Desired effect: Two top-level soups: Albums and Singles

"Albums" would contain all tracks that have the "source" field filled out, with layers underneath for artist and album. "Singles" would contain all tracks that don't have the source field filled out, with a layer underneath for genre.

So I figured I could start with a "search layer" to my "albums" soup that would return all the tracks that have a non-null source, then add artist and album layers underneath that. But I can't find a search syntax that does the non-null thing. The advanced search syntax seems to be different than that of emplode. Are searches for null and not null supported? If so, what's the right syntax?