rails/rails — pull request #6606 by amatsuda (2012-06-03 05:33:41+00:00)
Title: AR::Relation#model would be a better API than AR::Relation#klass

`model` feels more natural for programmers, and this would make library authors a bit happier since it's compatible with `DM::Collection`
https://github.com/datamapper/dm-core/blob/9d9f739/lib/dm-core/collection.rb#L45