Question

这很难。

我有一个col1, col2, col3, col4 1,'my friend's pet is a dog','Husky',True模型：

Activity

所以，如果我这样做：

class Activity < ActiveRecord::Base
    belongs_to :trackable, polymorphic: true
    scope :include_all, -> { includes(:trackable) }
    ...
end

上面的代码运行良好，但是如果我也想加载可跟踪记录的父级怎么办？那些模型也有不同的父母：

@activities = Activity.include_all模型：

Answer

class Answer < ActiveRecord::Base belongs_to :question has_many :activities, as: :trackable scope :include_all, -> { includes(:question) } ... end模型：

Post

class Post < ActiveRecord::Base belongs_to :blog has_many :activities, as: :trackable scope :include_all, -> { includes(:blog) } ... end模型：

Category

请注意，每个模型中的class Category < ActiveRecord::Base has_many :activities, as: :trackable scope :include_all, -> {} ... end范围显示要包含的关联。我尝试过

include_all

当带有class Activity < ActiveRecord::Base ... scope :include_all, -> { includes(trackable: :question) } ... end = Activity的{{1}}出现时，这将中断。

有什么想法吗？

Rick的回答是一个很好的方法，但是，有没有办法在另一个范围内使用关联范围？对于没有像trackable_type这样的父母的协会来说，这非常方便。

类似

Post

Answer 1

您可以在parent和Answer上定义一个附加的Post关联，以扩展trackable ducktype的接口：

class Answer < ActiveRecord::Base
  belongs_to :question
  belongs_to :parent, class_name: :Question, foreign_key: :question_id
  ...
end

class Post < ActiveRecord::Base
  belongs_to :blog
  belongs_to :parent, class_name: :Blog, foreign_key: :blog_id
  ...
end

class Activity < ActiveRecord::Base
  scope :include_all, -> { includes(trackable: :parent) }
  ...
end

Answer 2

钉了！如果将范围直接添加到belongs_to行，则关联将加载该范围。

class Activity < ActiveRecord::Base
    belongs_to :trackable, -> { include_all } , polymorphic: true
    ...
end

Rails：范围内与trackable_type的热切负载关联

2 个答案: