Ruby-on-rails 模块的 Rails 未定义方法

Rails undefined method for Module

提问by gprasant

In Rails, how do you use a specific method from a module. For eg,

在 Rails 中，如何使用模块中的特定方法。例如，

# ./app/controllers/my_controller.rb
class MyController < ApplicationController
  include MyModule 

  def action
    MyModule.a_method
  end

  private
  def a_method
    ...
  end
end

# ------------------------------------------------ #

# ./app/helpers/my_module.rb
module MyModule 
  def a_method
    ...
  end
end

MyControllerincludes MyModule. And in action,I want to use MyModule.a_method(Please note I also have a private a_methodin MyController and I don'twant to use this.)

MyController包括我的模块。而在action，我想用MyModule.a_method（请注意，我也有一个私人a_method的和myController的我并不想用这个。）

Things I've tried :

我尝试过的事情：

1) Defining the method in the module as self.

1）将模块中的方法定义为 self.

def self.a_method
end

2) Using the ::notation in controller (MyModule::a_method)

2)::在控制器 ( MyModule::a_method) 中使用符号

The error that I keep getting is Undefined method:a_method for MyModule:moduleFor now, I've resorted to using a different name for the modules method. But I'd like to know how to namespace the function with either the Module::or Module.notation

我不断收到的错误是 Undefined method:a_method for MyModule:module现在，我对模块方法使用了不同的名称。但我想知道如何使用Module::orModule.符号命名函数

[UPDATE - 11/24/2014]adding file structure in code, since Rails heavily relies on convention.

[更新 - 2014 年 11 月 24 日]在代码中添加文件结构，因为 Rails 严重依赖约定。

回答by jgraft

So I am not really sure what you are trying to accomplish with your module but a quick solution to get it working is below.

所以我不太确定你想用你的模块完成什么，但下面是一个让它工作的快速解决方案。

1. Move my_module.rb out of helpers and into lib/my_module.rb. The helpers directory is for methods that you use in your views. The convention is to utilize helpers that are namespaced after their respective controller or the application_helper.rb for global methods for your views. Not sure if that's what you are trying to accomplish with your module but wanted to throw that out there.
2. Create an initializer (you can all it whatever) in config/initializers/custom_modules.rb and add require 'my_module'
3. Update the a_method back to be self.a_method
4. You can now call MyModule.a_methodin your app

1. 将 my_module.rb 移出 helpers 并移入 lib/my_module.rb。helpers 目录用于您在视图中使用的方法。约定是使用命名空间位于其各自控制器或 application_helper.rb 之后的助手作为视图的全局方法。不确定这是否是您尝试使用模块完成的任务，但想将其扔掉。
2. 在 config/initializers/custom_modules.rb 中创建一个初始化程序（你可以随意）并添加 require 'my_module'
3. 将 a_method 更新为 self.a_method
4. 您现在可以MyModule.a_method在您的应用中调用

Don't forget to restart your server for changes to lib/my_module.rb to take effect.

不要忘记重新启动服务器以使对 lib/my_module.rb 的更改生效。

Also, a lot of people reference this postby Yehuda Katz as guidance on where to store code for your app. Thought it might be a helpful reference.

此外，很多人参考Yehuda Katz 的这篇文章作为关于在何处存储应用程序代码的指导。认为这可能是一个有用的参考。

回答by nicolas

if you include MyModule into MyController, all the "instance methods" of the first will be mixed-in into the 2nd.

如果将 MyModule 包含到 MyController 中，则第一个的所有“实例方法”都将混入到第二个中。

So if you only want to call MyModule.a_method, no needto include your module.

因此，如果您只想调用 MyModule.a_method，则无需包含您的模块。

Then you'd want to require (or better autoload) your module before using it. To do so place it in controllers/concerns/my_module.rb, rails (4 at least) should autoload it, otherwise require its file in an intializer

然后你会想要在使用它之前要求（或更好地自动加载）你的模块。为此，将其放置在控制器/问题/my_module.rb 中，rails（至少 4 个）应自动加载它，否则需要将其文件放在初始化器中

# my_module.rb
module MyModule 
  def self.a_method
    ...
  end
end

should work, but doing

应该工作，但做

# my_module.rb
module MyModule 
  extend self
  def a_method
    ...
  end
end

is more clean to me. You'd like to have a look to rails active support concernto understand the "rails way" on this topic.

对我来说更干净。您想查看 rails主动支持问题以了解有关此主题的“rails 方式”。