Generating random barcodes

barcode.rb

class Barcode < ActiveRecord::Base

  validates_presence_of :code
  validates_uniqueness_of :code
  validates_length_of :code, :is => 8

  def generate_random_code
    "#{self.batch}#{self.letters}#{self.numbers}"
  end

  def set_random_code
    self.code = generate_random_code
  end

  class << self

    def generate_barcodes(letter, batch_size)
      batch_size.times do
        self.generate_barcode(letter)
      end
    end

    def generate_barcode(letter)
      barcode = self.new_for_batch(letter)
      until barcode.valid? do
        barcode.set_random_code
      end
      barcode.save!
    end

    def new_for_batch(letter)
      barcode = self.new({:batch => letter})
      barcode.set_random_code
      barcode
    end

  end

protected

  def letters
    (0...3).map { (65 + rand(26)).chr }.join
  end

  def numbers
    '%04d' % rand(0...10000)
  end

end