Class Voucher < ActiveRecord::Base
  before_validation_on_create :generate_code

  def generate_code
    code = create_code
    
    #ensure that the voucher code is unique.
    @voucher = Voucher.find(:first, :conditions => "code = '#{code}'")
    while [email protected]?
      code = create_code
      @voucher = Voucher.find(:first, :conditions => "code = '#{code}'")
    end
    
    self.code = code
  end
  
  protected
  def create_code
    chars = ("A".."Z").to_a

    code = ""
    1.upto(VOUCHER_CODE_LENGTH) { |i| 
      code << chars[rand(chars.size-1)] 
      if i % 4 == 0 && i < VOUCHER_CODE_LENGTH
        code << "-"
      end
    }
    return code
  end
end

Can be used to generate a random code for an online voucher. You just need to set VOUCHER_CODE_LENGTH in your environment.rb or similar.

Generate codes for a online gift voucher

ruby

Rails