Using Mongoid 3.0.6.

class Cow
include Mongoid::Document

field :hash, :type => Hash
field :array, :type => Array
end

Cow.create(:hash => ['a', 'b'], :array => {:i => 2})
=> #<Cow _id: 50711b98f4d5d4ee0e000002, _type: nil, hash: ["a", "b"], array: {:i=>2}>

This is sort of worrisome. Is there a way to prevent this?