Contents

module Uuids

  # Stores uuids assigned to corresponding records.
  #
  # Attributes:
  # +value+:: A value of uuid as defined in
  #           {RFC4122}[http://www.ietf.org/rfc/rfc4122.txt].
  #           Assigned by default on creation. Cannot be set or edited manually.
  # +record+:: An AR record the uuid is assigned to.
  #            Required attribute. Can be changed.
  #
  # @example
  #     # Create the uuid
  #     uuid = Uuids::Uuid.create! record: some_record
  #
  #     # Find a record by uuid
  #     Uuid.find_by_value(uuid.value).record # => some_record
  #
  #     # Reassigns a uuid to another record
  #     uuid.update_attributes! record: another_record
  #
  class Uuid < ActiveRecord::Base
    self.table_name = :uuids_uuids

    # A format for UUID following RFC4122
    UUID_FORMAT = /[a-z\d]{8}-[a-z\d]{4}-[a-z\d]{4}-[a-z\d]{4}-[a-z\d]{12}/

    attr_readonly  :value
    belongs_to     :record, polymorphic: true

    validates :value, format: { with: UUID_FORMAT }, allow_nil: true
    validate  :record_present?

    before_create  :set_default_value
    before_destroy :forbid_destruction

    private

    # Validates record presence with a custom error message.
    def record_present?
      return if record
      errors.add :record, :blank, uuid: value
    end

    # Sets a new value by default
    def set_default_value
      self.value = SecureRandom.uuid unless value
    end

    # Forbids destruction of the record.
    def forbid_destruction
      errors.add :base, :destruction_forbidden
      false
    end
  end
end

Version data entries

3 entries across 3 versions & 1 rubygems

Version	Path
uuids-1.4.2	app/models/uuids/uuid.rb
uuids-1.4.1	app/models/uuids/uuid.rb
uuids-1.4.0	app/models/uuids/uuid.rb