Rails的多态的has_many：通过 [英] Rails polymorphic has_many :through

问题描述

我是从一个外部API拉一些数据，并想在本地缓存的结果。我有一个类搜索关键词，我想用几个不同的ActiveRecord类型，通过该表相关联 searchable_items 。我是pretty的肯定，我有表设置正确的事，但在我协会必须是错误的。

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.

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

我会希望能够做到像 SearchTerm.find_by_term（'搜索关键词'）。可搜寻（这将返回Foo和Bar对象的数组）然而， ，我得到的错误 找不到关联关系：在模型中搜索关键词searchable_items

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

在此先感谢任何见解，你可以提供给我！

Thanks in advance for any insight you can provide to me!

推荐答案

您需要的has_many补充：searchable_items 协会富，酒吧和搜索关键词模型，因为：通过=＆GT; ：searchable_items 选项是指联想

You need to add has_many :searchable_items association to Foo, Bar and SearchTerm models because :through => :searchable_items option refers to that association.

<一个href="http://guides.rubyonrails.org/association_basics.html#the-has_many-through-association">http://guides.rubyonrails.org/association_basics.html#the-has_many-through-association

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