Question

我在GitHub上贡献了一个ruby on rails应用程序，我遇到了以下情况：

我有以下模型，我想转换为多态：

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

我进行了以下更改以使其具有多态性：

执行数据库更改以删除team_id，project_id，application_id和user_id，并将commentable_id和commentable_type添加到comments表

在导轨指南中描述的模型中的修改：

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

虽然我在默认范围内使用它，但它不允许我使用默认范围并在下面的行中给出错误：

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

我很难改变以下模型：

class User < ActiveRecord::Base
end

class Application < ActiveRecord::Base
end

我是否需要在User和Application型号中进行以下更改？

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

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

提前致谢！

Answer 1

如果您的用户/应用程序对象需要注释，则添加

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

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

否则创建belongs_to / has_many关系不是多态的例如

class User < ActiveRecord::Base
  has_many :comments
end

class Application < ActiveRecord::Base
  has_many :comments
end

Ruby on Rails：多态关联混淆

1 个答案: