def assign_users
    ActiveRecord::Base.transaction do
      begin
        assign_to_all_users
        assign_by_given_roles
        assign_by_given_users
        assign_by_given_places

        true
      rescue
        raise ActiveRecord::Rollback
      end
    end
  end

  def reassing_users
    ActiveRecord::Base.transaction do
      begin
        remove_news_assignments
        assign_users
      rescue
        raise ActiveRecord::Rollback
      end
    end
  end