什么是覆盖的ActiveRecord的find两个模型和集合最彻底的方法？ [英] What's the cleanest way to override ActiveRecord's find for both models and collections?

问题描述

我有库code重写氩气的发现方法。我还包括了模块的所有关联类所以无论MyModel.find和@ parent.my_models.find工作，并应用正确的范围。

I have library code that overrides Ar's find method. I also include the module for all Association classes so both MyModel.find and @parent.my_models.find work and apply the correct scope.

我根据我的code脱will_paginate的：

I based my code off of will_paginate's:

a = ActiveRecord::Associations
returning([ a::AssociationCollection ]) { |classes|
  # detect http://dev.rubyonrails.org/changeset/9230
  unless a::HasManyThroughAssociation.superclass == a::HasManyAssociation
    classes << a::HasManyThroughAssociation
  end
}.each do |klass|
  klass.send :include, Finder::ClassMethods
  klass.class_eval { alias_method_chain :method_missing, :paginate }
end

我的问题是，我只是想覆盖发现者对于某些型号。目前，我需要延长这是由所有模型共享的所有关联的集合类。我知道我可以通过传递一个模块扩展每个模型关联：

My problem is, I only want to override the finders for some models. Currently I need to extend all association collection classes which are shared by all models. I know I can extend associations per model by passing a module:

has_many :things, :extend => SomeCustomMethods

但我的图书馆基本上是ActiveRecord的插件，所以我想为适用于两种型号和范围的集合，而不会影响应用程序中的所有型号可插拔取景器扩展干净的习惯。

But my library is basically am ActiveRecord plugin, so I'd like a clean convention for plugable finder extensions that apply to both the model and scoped collections without affecting all models in the application.

推荐答案

您希望重写 find_every ，这是将最终运行AR方法的find_by_sql 与相应的查询。覆盖查找不会为定制的发现者工作，它只是更加脆弱。

You want to override find_every, which is the AR method that will ultimately run find_by_sql with the corresponding query. Overriding find won't work for customized finders, and it's just more fragile.

但要与其他插件兼容，你不能只重载此方法。相反，它的别名和做后，你想要什么叫原实：

But to be compatible with other plugins you can't just overload this method. Instead, alias it and call the original implementation after doing what you want:

module MyPlugin
  def self.included(base)
    class << base
      alias_method :find_every_without_my_plugin, :find_every
      def find_every(*args)
        # do whatever you need ...
        find_every_without_my_plugin(*args)
      end
    end
  end
end

ActiveRecord::Base.send :include, MyPlugin

这将使你的插件的所有类。你怎么要控制使用哪个型号？也许一个标准插件存取？

This will enable your plugin for all classes. How do you want to control which models are enabled? Maybe a standard plugin accessor?

class User < ActiveRecord::Base
  my_plugin
end

要支持这一点，你需要移动类＆LT;＆LT;基一类方法（因此基础应自）。像：

To support this you need to move the class << base to a class method (thus base should be self). Like:

module MyPlugin
  def self.included(base)
    class << base
      base.extend ClassMethods
    end
  end

  module ClassMethods
    def my_plugin
      class << self
        alias_method :find_every_without_my_plugin, :find_every
        # ...
      end
    end
  end
end

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