通过模块共享范围？

Question

我想通过将共享范围移动到模块中来干掉几个模型,例如:

module CommonScopes
  extend ActiveSupport::Concern

  module ClassMethods
    scope :ordered_for_display, order("#{self.to_s.tableize}.rank asc")
  end
end

我还想创建测试模块的共享规范.不幸的是,当我尝试在我的模型中包含共享范围时,我得到:

undefined method `order' for CommonScopes::ClassMethods:Module

有任何想法吗？谢谢!

Answer 1

与rails 4 作用域语法一样,您可以简单地使用lambda来延迟代码的执行(也可以在rails 3中运行):

module CommonScopes
  extend ActiveSupport::Concern

  included do
    scope :ordered_for_display, -> { order("#{self.to_s.tableize}.rank asc") }
  end
end

Answer 2

您可以使用instance_eval

module CommonScopes
  extend ActiveSupport::Concern

  def self.included(klass)
    klass.instance_eval do
      scope :ordered_for_display, order("#{self.to_s.tableize}.rank asc")
    end
  end
end