ruby-on-rails - 在 Rails 5 Application Record 类中包含一个模块

Question

我正在使用 Application Record 来简化整个应用程序的共享逻辑。

这是一个为 bool 值及其逆函数编写作用域的示例。这很有效:

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true

  def self.boolean_scope(attr, opposite = nil)
    scope(attr, -> { where("#{attr}": true) })
    scope(opposite, -> { where("#{attr}": false) }) if opposite.present?
  end
end

class User < ApplicationRecord
  boolean_scope :verified, :unverified
end

class Message < ApplicationRecord
  boolean_scope :sent, :pending
end

我的 Application Record 类已经足够长，所以我可以将它分解成单独的模块并根据需要加载它们。

这是我尝试的解决方案:

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
  include ScopeHelpers
end

module ScopeHelpers
  def self.boolean_scope(attr, opposite = nil)
    scope(attr, -> { where("#{attr}": true) })
    scope(opposite, -> { where("#{attr}": false) }) if opposite.present?
  end
end

class User < ApplicationRecord
  boolean_scope :verified, :unverified
end

class Message < ApplicationRecord
  boolean_scope :sent, :pending
end

在这种情况下，我没有收到加载错误，但是 boolean_scope 在 User 和 Message 上未定义。

有没有办法确保包含的模块在适当的时间加载并可供 Application Record 及其继承模型使用？

---

我还尝试让模型直接包含模块，但这并没有解决问题。

module ScopeHelpers
  def self.boolean_scope(attr, opposite = nil)
    scope(attr, -> { where("#{attr}": true) })
    scope(opposite, -> { where("#{attr}": false) }) if opposite.present?
  end
end

class User < ApplicationRecord
  include ScopeHelpers
  boolean_scope :verified, :unverified
end

class Message < ApplicationRecord
  include ScopeHelpers
  boolean_scope :sent, :pending
end

Answer 1

作为@Pavan 答案的替代方案，您可以这样做:

module ScopeHelpers
  extend ActiveSupport::Concern # to handle ClassMethods submodule

  module ClassMethods
    def boolean_scope(attr, opposite = nil)
      scope(attr, -> { where(attr => true) })
      scope(opposite, -> { where(attr => false) }) if opposite.present?
    end
  end
end

# then use it as usual
class ApplicationRecord < ActiveRecord::Base
  include ScopeHelpers
  ...
end