`ClassName.constants`在Rails应用中返回空数组 [英] `ClassName.constants` returning empty array in Rails app

问题描述

我正在使用Rails 3应用程序，并且在lib文件夹中有一个类的层次结构，例如:

I'm working on a Rails 3 app, and I've got a hierarchy of classes in my lib folder, e.g.:

lib
├── assets
├── tasks
│   └── import.rake
└── importer
    ├── base.rb
    └── source
        ├── facebook.rb
        ├── google.rb
        └── twitter.rb

我更新了config/application.rb，以包括以下行:

I've updated config/application.rb to include this line:

config.autoload_paths += %W(#{config.root}/lib)

然后在Importer::Base内部，我有一个实例方法试图加载Provider模块中的所有类，例如:

Then inside of Importer::Base, I have an instance method that attempts to load all classes in the Provider module, e.g.:

Importer::Source.constants.each do |class_name|
  Importer::Source.const_get(class_name).process
end

lib/importer/base中的三个类的类层次结构类似于:

The three classes in lib/importer/base have a class hierarchy similar to:

module Importer
  module Source
    class Facebook
      # ...
    end
  end
end

当我调用此方法时，Importer::Source.constants最终返回一个空数组.如果直接按名称引用这些类，则这些类似乎已正确装入，但是在constants调用中无法访问.我该如何解决?

When I call this method, Importer::Source.constants ends up returning an empty array. The classes appear to be lazy-loaded properly if I reference them by name directly, but they are not accessible in the constants call. How can I fix this?

推荐答案

使用@apneadiving的建议，我可以通过将以下行添加到我的base.rb文件的开头来解决此问题:

Using @apneadiving's suggestion, I was able to fix this by adding this line to the beginning of my base.rb file:

Dir[Rails.root.join('lib/importer/source/**/*.rb')].each(&method(:require))

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