要求 Rails 模型具有来自模块的特定方法

Question

我有一个模块，它定义了一些方法，并包含在一些 Rails 模型中。我希望包含模块的模型定义一些特定的方法（好像我希望它们实现一个接口）。

但是，当我希望模型有一个方法，结果证明是活动记录已经定义的属性时，问题就出现了。

我的代码如下：

Module Mod
  included do
    # some code...
    # require some methods to be implemented by including class
    def do_x
      raise('not implemented, please override me')
    end

    def name
      raise('not implemented, please override me')
    end
  end
end

class Supplier < ApplicationRecord
  # already has a name attribute
  include Mod

  # this overrides do_x of mod
  def do_x
    # some code...
  end
end

Supplier 类的 name 方法实际上被模块 Mod 的方法覆盖，这不是我想要的行为。

Answer 1

Module Mod
  # some code...  (within an included block)
  # require some methods to be implemented by including class
  def do_x
    raise('not implemented, please override me')
  end

  def name
    raise('not implemented, please override me')
  end
end

class Supplier < ApplicationRecord
  include Mod

  # this overrides do_x of mod
  def do_x
    # some code...
  end
end

从included 块中删除那些似乎对我有用。

https://api.rubyonrails.org/classes/ActiveSupport/Concern.html#method-i-included 解释“在基类的上下文中评估给定块，以便您可以在此处编写类宏。当您定义多个包含块时，它会引发异常。”它通常用于定义关系、范围、验证

一个相关且有用的 Stackoverflow 问题和答案：Ruby modules - included do end block ，具体来说，https://stackoverflow.com/a/28009847/2526423

=======

本地工作示例：

irb(main):070:0> Author.create!
   (0.1ms)  SELECT sqlite_version(*)
   (0.1ms)  begin transaction
  Author Create (0.5ms)  INSERT INTO "authors" ("created_at", "updated_at") VALUES (?, ?)  [["created_at", "2020-03-29 22:06:28.202124"], ["updated_at", "2020-03-29 22:06:28.202124"]]
   (0.8ms)  commit transaction
=> #<Author id: 2, name: nil, year: nil, created_at: "2020-03-29 22:06:28", updated_at: "2020-03-29 22:06:28", uid: nil>
irb(main):071:0> author.name
=> nil
irb(main):072:0> author.do_x
class: do_x
=> nil

app/models/author.rb

require 'do_x_mod'

class Author < ApplicationRecord
  include DoXMod

  def do_x
    puts "class: do_x"
  end
end

lib/do_x_mod.rb

module DoXMod
  # included do
    # some code...
    # require some methods to be implemented by including class
    def do_x
      puts "module: do_x"
      raise('not implemented, please override me')
    end

    def name
      puts "module: name"
      raise('not implemented, please override me')
    end
  # end
end