我应该如何使用的构建方法alias_method_chain？

问题描述

我使用on Rails的Ruby的3.2.13，我想正确使用 alias_method_chain：构建，：OPTION_NAME 语句，因为我得到一个奇怪的错误。即，...

I am using Ruby on Rails 3.2.13 and I would like to properly use the alias_method_chain :build, :option_name statement since I am getting a strange error. That is, ...

......我的控制器文件我有：

... in my controller file I have:

class Articles::CommentsController < ApplicationController
  def create
    @articles_comment = @article.comments.build(params[:comment])
    ...
  end
end

......在我的模型文件我有：

... in my model file I have:

class Articles::Comment < ActiveRecord::Base
  def self.build_with_option_name
    ...
  end

  alias_method_chain :build, :option_name
end

当我运行创建控制器操作，我得到的日志出现以下错误：

When I run the create controller action I get the following error in log:

ActionController::RoutingError (undefined method `build' for class `Articles::Comment'):
  app/models/articles/comment.rb:5:in `<class:Comment>'

的我应该如何使用 alias_method_chain 为建立方法？的或者，也许好，我应该继续以另一种方式达到我想什么做（例如，我应该覆盖建立方法在文章::注释模式，而不是使用 alias_method_chain ）？

How should I use the alias_method_chain for the build method? Or, maybe better, should I proceed in another way to reach what I would like to make (for example, should I overwrite the build method in the Articles::Comment model instead of using alias_method_chain)?

的注意I 的：我不知道是否有帮助，但建立法是指联想（ @ article.comments ）。更多的，我不说出建立方法在文章::评论模型，因为它应该是加/在Ruby on Rails框架本身（我认为这是通过元编程制作）附加的类。

Note I: I don't know if it helps, but the build method refers to an association (@article.comments). More, I do not state the build method in the Articles::Comment model because it should be "added" / "attached" to the class by the Ruby on Rails framework itself (I think it is made through meta-programming).

的注二的：考虑到新方法，而不是建时发生同样的错误;也就是说，当使用 alias_method_chain：新：OPTION_NAME

Note II: The same error occurs when considering the new method instead of build; that is, when using alias_method_chain :new, :option_name.

推荐答案

正如你所说的，是建立在联想代理定义的方法。你可以做的就是用联想扩展，因此模型中可以传递块到你的has_many调用，将被视为给定association_proxy延期：

As you said, build is a method defined on association proxy. What you can do is to use association extensions, so in a model you can pass a block to your has_many call, which will be treated as an extension for given association_proxy:

class Article < ActiveRecord::Base
  ...
  has_many :comments do
    alias_method_chain :build, :option_name
  end

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