Module concern for generating token

tokenable.rb

module Tokenable
  extend ActiveSupport::Concern

  included do
    before_save :ensure_token

    def ensure_token
      generate_token(length: 32) if token.blank?
    end

    private

    def generate_token(length: 32)
      begin
        self.token = SecureRandom.urlsafe_base64(length).gsub(/[\-_]/, "").first(length)
      end while self.class.where(token: token).exists?
    end
  end
end