A small library for validating Australian Business Numbers (ABN)

gem install abn

require 'abn'

ABN.new("12042168743").valid?
=> true

ABN.valid?("12042168743")
=> true

ABN.valid?("12042168744")
=> false

Version 1.3 of this gem had an active record mixin for validating ABN fields in models. I removed it in version 2.0 to avoid complications of supporting active record 2.x and 3.x (and Datamapper, Mongoid, etc).

To validate an ABN field in your model add the ABN gem to your Gemfile and use the following pattern:

class Business < ActiveRecord::Base

validate :validate_abn

private

def validate_abn
  if self.abn.present && !ABN.valid?(self.abn)
    self.errors.add(:abn, "is not a valid ABN")
    false
  end
end

end

• http://www.clearwater.com.au/code
• https://en.wikipedia.org/wiki/Australian_Business_Number