用concerns来管理models

# autoload concerns

module YourApp

  class Application < Rails::Application

    config.autoload_paths += %W(

#{config.root}/app/controllers/concerns

#{config.root}/app/models/concerns

)

  end

end

# app/models/concerns/trashable.rb

module Trashable

  extend ActiveSupport::Concern

  

  included do

    default_scope where(trashed: false)

    scope :trashed, where(trashed: true)

  end

  

  def trash

    update_attribute :trashed, true

  end

end

# app/models/message.rb

class Message < ActiveRecord::Base

  include Trashable, Subscribable, Commentable, Eventable

end