Ruby-on-rails Rails 多态 has_many :through
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Rails polymorphic has_many :through
提问by lyricat
I'm pulling some data from an external API and would like to cache the results locally. I have a class SearchTerm, which I would like to be associated with a few different ActiveRecord types through the table searchable_items. I'm pretty sure I have the tables set up correctly, but something in my associations must be wrong.
我正在从外部 API 中提取一些数据，并希望在本地缓存结果。我有一个class SearchTerm，我想通过表将它与几个不同的 ActiveRecord 类型相关联searchable_items。我很确定我的表格设置正确，但我的关联中的某些东西一定是错误的。
class Foo < ActiveRecord::Base
has_many :search_terms, :as => :searchable, :through => :searchable_items
end
class Bar < ActiveRecord::Base
has_many :search_terms, :as => :searchable, :through => :searchable_items
end
class SearchTerm < ActiveRecord::Base
has_many :searchables, :through => :searchable_items
end
class SearchableItem < ActiveRecord::Base
belongs_to :search_term
belongs_to :searchable, :polymorphic => true
end
I would expect to be able to do something like SearchTerm.find_by_term('SearchTerm').searchables(and it would return an array of Foo and Bar objects) however, I get the error
Could not find the association :searchable_items in model SearchTerm
我希望能够做类似的事情SearchTerm.find_by_term('SearchTerm').searchables（它会返回一个 Foo 和 Bar 对象的数组）但是，我得到了错误
Could not find the association :searchable_items in model SearchTerm
Thanks in advance for any insight you can provide to me!
在此先感谢您提供给我的任何见解！
采纳答案by Heikki
You need to add has_many :searchable_itemsassociation to Foo, Barand SearchTermmodels because :through => :searchable_itemsoption refers to that association.
您需要将has_many :searchable_items关联添加到Foo,Bar和SearchTerm模型，因为:through => :searchable_itemsoption 指的是该关联。
http://guides.rubyonrails.org/association_basics.html#the-has_many-through-association
http://guides.rubyonrails.org/association_basics.html#the-has_many-through-association
