github.com/trliner/fake_id

class SecretAgentAlias < ActiveRecord::Base
  include FakeId

  attr_accessible :document_type_id

  fake_ids_for :document_type, {
    :drivers_license => 1,
    :passport => 2
  }
end

alias = SecretAgentAlias.new(:document_type_id = 1)
alias.document_type
=> :drivers_license

alias.document_type = :passport
alias.document_type
=> :passport

alias.passport?
alias.passport
=> true

alias.drivers_license?
alias.drivers_license
=> false

SecretAgentAlias.document_types
=> [:drivers_license, :passport]

SecretAgentAlias.document_type_mappings
=> {1=>:drivers_license, 2=>:passport}

SecretAgentAlias.lookup_document_type(1)
=> :drivers_license

SecretAgentAlias.lookup_document_type(:passport)
=> 1

SecretAgentAlias.drivers_license
SecretAgentAlias.not_passport
SecretAgentAlias.document_type_is(:drivers_license)
SecretAgentAlias.document_type_is_not(:passport)
SecretAgentAlias.document_type_in(:drivers_license, :passport)
SecretAgentAlias.document_type_not_in(:drivers_license, :passport)