unserialize_attribute

# File activerecord/lib/active_record/attribute_methods.rb, line 291
    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