ruby-on-rails - Rails，在模型中有没有办法提供自上次更新以来的不同？

Question

给定一个模型，如:

class SentenceItem < ActiveRecord::Base

  after_update :send_changes

  def send_changes
     #### Is it possible to do a diff here with dirty/changed? Showing what's changed since the last save?
  end

end

并且句子模型有一个文本字段。

是否可以在此处使用dirty/changed做一个差异？显示自上次保存以来发生了什么变化？

谢谢

Answer 1

是的，有办法。来自 ActiveModel::Dirty文档:

新实例化的对象不变:

person = Person.find_by_name('Uncle Bob')
person.changed?       # => false

更改名称:

person.name = 'Bob'
person.changed?       # => true
person.name_changed?  # => true
person.name_was       # => 'Uncle Bob'
person.name_change    # => ['Uncle Bob', 'Bob']
person.name = 'Bill'
person.name_change    # => ['Uncle Bob', 'Bill']

哪些属性发生了变化？

person.name = 'Bob'
person.changed        # => ['name']
person.changes        # => { 'name' => ['Bill', 'Bob'] }