如何将 ActiveRecord 属性辅助方法添加到虚拟属性?

本文介绍了如何将 ActiveRecord 属性辅助方法添加到虚拟属性?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

ActiveRecord 提供属性辅助方法，例如 _? 和脏"方法(_changed? 等)

ActiveRecord offers attribute helper methods such as _? and the "dirty" methods (_changed? etc.)

是否有 Rails 方法可以在非持久化或虚拟"属性上定义这些相同的方法?

Is there a Rails way to define these same methods on non-persisted or "virtual" attributes?

我希望是这样的:

class MyClass < ActiveRecord::Base some_macro :my_attribute end $ @my_class = MyClass.new $ @my_class.my_attribute? # => false $ @my_class.my_attribute_changed? # => false

推荐答案

好吧，这确实是值得研究的有趣事情.显然没有直接的方法可以做到这一点......我发现了两件事

Well this was certainly something interesting to investigate. Apparently there is not a straight forward way to do this... here are two things I found

从 2009 年起

从 2011 年开始 - 加强了 2009 年的帖子但让它更干净一点.您创建一个更新属性哈希的模块.来自 Brandon Weiss 的帖子:

From 2011 - reinforces the 2009 post but makes it a bit cleaner. You create a module that updates the attribute hash. From the Brandon Weiss post:

# app/models/dirty_associations.rb module DirtyAssociations attr_accessor :dirty def make_dirty(record) self.dirty = true end def changed? dirty || super end end # app/models/lolrus.rb class Lolrus include DirtyAssociations has_and_belongs_to_many :buckets, :after_add => :make_dirty, :after_remove => :make_dirty end

还有这个插件 此处提到，但我不确定它对您有多大用处.

There is also this plugin mentioned here but I am not sure how useful it is for you.