gistfile1.rb

class Foo
 include Mongoid::Document
 field :enabled, :type=>Boolean, :default=>false
 scope :on, where(:enabled=>true)
 scope :off, where(:enabled=>false)
end


irb> Foo.on.count
0
irb> Foo.off.count
100
irb> Foo.off.limit(10).update_all(:enabled=>true)
irb> Foo.on.count
100
irb> Foo.off.count
0

Expected: Foo.on.limit => 10