在 Rails 中包含模块

Question

考虑多个具有重叠字段和功能的 ActiveRecord 类，并且其中许多重叠字段具有相同的验证。 我正在尝试共享验证，但如果满足条件（基于模型的非重叠属性之一），则不运行共享代码。

class Book < ApplicationRecord
  include SharedValidation
end

class Magazine < ApplicationRecord
  include SharedValidation
end

module SharedValidation
  extend ActiveSupport::Concern
  include ActiveModel::Validations

  validates_presence_of :name, :publisher, :author
end

所以假设Magazine.is_deleted是一个 Magazine-only 字段，我们只想在 is_deleted 为false 时运行共享验证。 关于如何在课堂上实现这一点的任何想法？

---

注意：我尝试通过执行字段检测和评估来修改模块，但不确定这是否有意义或是否有效：

module SharedValidation
  extend ActiveSupport::Concern
  include ActiveModel::Validations

  included do
    proc do |rcd|
      has_deleted_field = self.column_names.include?('is_deleted') 
      
      if (has_deleted_field && !rcd.is_deleted) || !has_deleted_field
        validates_presence_of :name, :publisher, :author
      end 
    end
  end
end

Answer 1

看起来您可以将条件添加到验证方法中（在 SharedModule 中），而不是有条件地包含模块。

使用您的样品：

class Book < ApplicationRecord
  include SharedValidations
end

class Magazine < ApplicationRecord
  include SharedValidations
end

module SharedValidations
  extend ActiveSupport::Concern
  include ActiveModel::Validations

  def deleted
    return unless self.class.column_names.include?("is_deleted")

    is_deleted
  end

  included do
    validates :name, :publisher, presence: true, unless: :deleted
  end
end

Magazine 有name 、 publisher和is_deleted列。 Book 只有name ， publisher没有is_deleted 。

看起来这个设置有效。

irb> book = Book.new()
=> #<Book id: nil, name: nil, publisher: nil, created_at: nil, updated_at: nil>
irb> book.valid?
=> false
irb> book.errors.full_messages
=> ["Name can't be blank", "Publisher can't be blank"]

irb> magazine = Magazine.new
=> #<Magazine id: nil, name: nil, publisher: nil, is_deleted: nil, created_at: nil, updated_at: nil>
irb> magazine.valid?
=> false
irb> magazine.errors.full_messages
=> ["Name can't be blank", "Publisher can't be blank"]

irb> magazine.is_deleted=true
=> true
irb> magazine.valid?
=> true