Currently we have first_or_create and first_or_initialize. Both of these methods pick apart the query criteria and attempt to mass-assign attributes.

Often my query contains non-mass-assignable attributes, which gives warnings. I'd prefer to have a much simpler method first_or_new like so:

module Mongoid
  module Document
    module ClassMethods
      def first_or_new(attrs = {})
        first || self.new(attrs)
      end
    end
  end
end