gistfile1.rb

    # Reset id and @new_record if the transaction rolls back.
    def rollback_active_record_state!
      id_present = has_attribute?(self.class.primary_key)
      previous_id = id
      previous_new_record = new_record?
      yield
    rescue Exception
      @new_record = previous_new_record
      if id_present
        self.id = previous_id
      else
        @attributes.delete(self.class.primary_key)
        @attributes_cache.delete(self.class.primary_key)
      end
      raise
    end