class CoAuthor include Mongoid::Document LANGUAGE_TYPES = [ "English", "Chinese" ] field :name_id, type: BSON::ObjectId field :co_author, localize: true field :email field :type VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i validates :email, format: { with: VALID_EMAIL_REGEX }, uniqueness: { case_sensitive: false } validates :co_author, presence: true before_save { |coauthor| coauthor.email = email.downcase } end