Question

我在Rails初始化程序中有以下代码：

module Mongoid::ActiveRecordBridge
  extend ActiveSupport::Concern

  included do
    def self.belongs_to_record(association_name, options={})
      association_class = (options[:class_name] || association_name.to_s.singularize.classify).constantize
      # index(#{ association_name }_id: 1)
      class_eval <<-EOS
        field :#{ association_name }_id, type: Integer
        def #{ association_name }
          @#{ association_name } ||= #{ association_class }.where(id: #{ association_name }_id).first
        end
        def #{ association_name }=(object)
          @#{ association_name } = object
          self.#{ association_name }_id = object.try :id
        end
      EOS
    end
  end
end

MyCode.all.map do |class_code|
  dynamic_class = "#{class_code.code}_field".classify
  Object.const_set dynamic_class, Class.new do
    include Mongoid::Document
    include Mongoid::ActiveRecordBridge

    belongs_to_record :classification_code
  end
end

它成功创建了类对象，因此如果class_code是SomeField，那么SomeField将被初始化。但是，当我运行以下命令时，它返回false：

SomeField.respond_to? :belongs_to_record  => false

然而，如果我在Rails控制台中构建另一个对象，它可以正常工作：

2.1.2 :003 > SomeRandomField = Class.new do
2.1.2 :004 >     include Mongoid::Document
2.1.2 :005?>   include Mongoid::ActiveRecordBridge
2.1.2 :006?>   belongs_to_record :classification_code
2.1.2 :007?>   end
 => SomeRandomField 
2.1.2 :008 > SomeRandomField.respond_to? :belongs_to_record
 => true

为什么当我在初始化程序中执行它时，它不起作用，但在Rails控制台中它可以工作？

Answer 1

这是因为该块已附加到Object.const_set，而不是Class.new

使用类似的东西：

klass = Class.new do
  include Mongoid::Document
  include Mongoid::ActiveRecordBridge

  belongs_to_record :classification_code
end

Object.const_set dynamic_class, klass

或使用括号来强制执行正确的分组。

ruby class.new块没有被触发

1 个答案: