Tokenable with settable token name

discussion.rb

class Discussion < ActiveRecord::Base
  include Tokenable
  set_token_field_name :other_token_name
end

tokenable.rb

module Tokenable
  extend ActiveSupport::Concern

  included do
    before_validation :set_token, on: :create, unless: :token?
    validates :token, uniqueness: true
    set_token_field_name :token
  end

  def to_param; send(self.class.token_field_name); end

  private

  def set_token
    self.send("#{self.class.token_field_name}=", SecureRandom.hex(5))
  end

  module ClassMethods
    attr_accessor :token_field_name

    def set_token_field_name(name)
      self.token_field_name = name
    end

    def t(token)
      find_by(token_field_name => token)
    end

    def t!(token)
      find_by!(token_field_name => token)
    end

    def [](token)
      t(token)
    end
  end
end