Contents

module Pipeline
  # Extends ActiveRecord::Base to provide attributes that are saved in a nested
  # transaction when updated through a setter.
  #
  # NOTE: When the extended attributes are updated, the entire record is saved
  #
  # Example:
  #   class Car < ActiveRecord::Base
  #     transactional_attrs :state, :engine_state
  #     
  #     def run
  #       self.engine_state = :on if self.state == :on
  #     end
  #   end
  #
  #   car = Car.new
  #   car.state = :on # this will save the record in a transaction
  #   car.run # Record will be saved again, since #run updates :engine_state
  module TransactionalAttribute
    def self.included (base)
      base.extend(ClassMethods)
    end

    module ClassMethods #:nodoc:
      def transactional_attrs(*attributes)
        attributes.each do |attribute|
          class_eval <<-EOD
            def #{attribute.to_s}=(value)
              ActiveRecord::Base.transaction(:requires_new => true) do
                write_attribute('#{attribute.to_s}', value)
                save!
              end
            end
          EOD
        end
      end
      
      alias_method :transactional_attr, :transactional_attrs
    end
  end
end

ActiveRecord::Base.send(:include, Pipeline::TransactionalAttribute)

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
pipeline-0.0.9	lib/pipeline/core_ext/transactional_attribute.rb