trabajo-afectivo/app/models/token.rb

class Token < ActiveRecord::Base
  before_create           :generate_token

  belongs_to              :user

  def self.check( data )

    # fetch token
    token = Token.where( :action => data[:action], :name => data[:name] ).first
    return if !token
    
    # check if token is still valid
    if token.created_at < 1.day.ago

      # delete token
      token.delete
      token.save
      return
    end

    # return token if valid
    return token.user
  end

  private
    def generate_token
      begin
        self.name = SecureRandom.hex(20)
      end while Token.exists?( :name => self.name )
    end
end