grater doesn't take a collection as a type argument, only a case class or a trait/abstract class whose concrete representations are case classes. Since you're just querying for a map, just extract the values you need out of the DBObject using getAs[T].

Number may not be a supported type in Salat - I've certainly never tried it. If you need Number you can write a custom transformer or send a pull request to add real support to Salat.

Related Query

More Query from same tag