Ruby on Rails：多態關聯混亂

Question

我正在GitHub上的ruby on rails應用程序之一中遇到以下情況：

我有以下要轉換為多態的模型：

class Comment < ActiveRecord::Base
  belongs_to :team
  belongs_to :user
  belongs_to :application
  belongs_to :project
end

class Team < ActiveRecord::Base
  has_many :comments
end

class Project < ActiveRecord::Base
  has_many :comments, -> { order('created_at DESC') }, dependent: :destroy
end

class User < ActiveRecord::Base
end

class Application < Rails::Application
end

我進行了以下更改以使其具有多態性：

對已刪除的team_id ， project_id ， application_id和user_id進行數據庫更改，並將commentable_id和commentable_type添加到comments表。

在rails指南中描述的模型修改：

class Comment < ActiveRecord::Base
  belongs_to :commentable, polymorphic: true
end

class Team < ActiveRecord::Base
  has_many :comments, as: :commentable
end

class Project < ActiveRecord::Base
  has_many :comments, as: :commentable, -> { order('created_at DESC') }, dependent: :destroy
end

當我將其與默認范圍一起使用時，它不允許我與默認范圍一起使用，並在以下行中給出錯誤：

has_many :comments, as: :commentable, -> { order('created_at DESC') }, dependent: :destroy

我很困惑要更改以下模型：

class User < ActiveRecord::Base
end

class Application < ActiveRecord::Base
end

我需要對User和Application模型進行以下更改嗎？

class User < ActiveRecord::Base
  has_many :comments, as: :commentable
end

class Application < ActiveRecord::Base
  has_many :comments, as: :commentable
end

提前致謝！

Answer 1

如果您的用戶/應用程序對象需要注釋，則添加

class User < ActiveRecord::Base
  has_many :comments, as: :commentable
end

class Application < ActiveRecord::Base
  has_many :comments, as: :commentable
end

否則創建不是多態的Eg的屬屬關系。

class User < ActiveRecord::Base
  has_many :comments
end

class Application < ActiveRecord::Base
  has_many :comments
end