Similar to the new slice functionality

db.foo.find( {} , { likes: { $only: [user_1, user_2]} } ) and it would return the list of user_ids that were found

My original idea was to recommend something like this, but mstearn recommended the one above instead.

db.foo.find( {} , { likes: { $has: user_1 } } ) and it would use return True/False

Because I just want the objects, and I want to know if the user liked each one without returning the full list of likes.