Ruby on Rails - 如何在after_filter中获取已更改的对象？

Question

我正在为Ruby on Rails 3中的用户创建操作跟踪。我想在控制器中使用after_filter方法，但我不知道如何在我的action_tracking方法中获取当前对象或当前操作。任何解决方案

# some_controller.rb 
class SomeController < ApplicationController 
    after_filter :action_tracking, only: [ :create, :update, :delete ] 
    ... 
end 

# application_controller.rb 
class ApplicationController < ActionController::Base 
    def action_tracking 
    action = <get name of action> # create, update or delete... 
    <object> = <get changed object> # event, user... 
    changes = <object>.changes  # { 'title' => ["Title", "New Title"] } 
    <object>.tracking.create(action, changes) 
    end 
end 

Answer 1

def action_tracking 
    action = params[:action] 
    changes = changed_object.changes 
    changed_object.tracking.create(action, changes) 
end 

# override for each controller 
# there is no way to know this in a generic way, unless you use something 
# like inherited_resources, or active scaffold, where the objects is "known" 
def changed_object 
    @user 
end