不能在模型中包含模块 [英] Cannot include module in model

问题描述

我正在使用

Ruby version              1.8.7
Rails version             3.0.3

我的 rails 应用程序的每个模型中都有一个名为 alive 的方法:

I have a method called alive in every model of my rails app:

  def alive
    where('deleter is null')  
  end   

我不想在每个模型中都复制这段代码，所以我做了一个/lib/life_control.rb

I don't want to copy this code in every model so I made a /lib/life_control.rb

module LifeControl    
  def alive
    where('deleter is null')  
  end   

  def dead
    where('deleter is not null')  
  end    
end

在我的模型(例如 client.rb)中我写道:

and in my model (for example client.rb) I wrote:

class Client < ActiveRecord::Base
  include LifeControl   
end

在我的 config/enviroment.rb 中我写了这一行:

and in my config/enviroment.rb I wrote this line:

require 'lib/life_control'

但现在我得到一个无方法错误:

but now I get a no method error:

NoMethodError in
ClientsController#index

undefined method `alive' for
#<Class:0x10339e938>

app/controllers/clients_controller.rb:10:in
`index'

我做错了什么?

推荐答案

include 会将这些方法视为实例方法，而不是类方法.你想要做的是:

include will treat those methods as instance methods, not class methods. What you want to do is this:

module LifeControl    
  module ClassMethods
    def alive
      where('deleter is null')  
    end   

    def dead
      where('deleter is not null')  
    end    
  end

  def self.included(receiver)
    receiver.extend ClassMethods
  end
end

这样，alive 和 dead 将可用于类本身，而不是其实例.

This way, alive and dead will be available on the class itself, not instances thereof.

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