def download_users(id)
      doc = permissions_doc(id)
      return [] if doc.nil?
      users = Array(doc[self.class.read_user_field]) + Array(doc[self.class.edit_user_field])
      Rails.logger.debug("[CANCAN] download_users: #{users.inspect}")
      users
    end
def download_users(id)
      doc = permissions_doc(id)
      return [] if doc.nil?
      users = Array(doc[self.class.read_user_field]) + Array(doc[self.class.edit_user_field])
      Rails.logger.debug("[CANCAN] download_users: #{users.inspect}")
      users
    end
Grant all users with read or edit access permission to download