instance method unserialize_attribute

# File activerecord/lib/active_record/attribute_methods/read.rb, line 128
      def unserialize_attribute(attr_name)
        unserialized_object = object_from_yaml(@attributes[attr_name])

        if unserialized_object.is_a?(self.class.serialized_attributes[attr_name]) || unserialized_object.nil?
          @attributes.frozen? ? unserialized_object : @attributes[attr_name] = unserialized_object
        else
          raise SerializationTypeMismatch,
            "#{attr_name} was supposed to be a #{self.class.serialized_attributes[attr_name]}, but was a #{unserialized_object.class.to_s}"
        end
      end