使用 STI 时 Rails 5.0 不获取多态关联答案

【问题标题】：Rails 5.0 not fetching polymorphic association when STI is used使用 STI 时 Rails 5.0 不获取多态关联
【发布时间】：2018-09-18 06:34:20
【问题描述】：

gem 'rails', '4.2.7.1'

class Property < Accommodation  
   has_many :attachments, as: :attached_item, dependent: :destroy  
end

class Accommodation < ActiveRecord::Base;
end

class Attachment < ActiveRecord::Base
     belongs_to :attached_item, polymorphic: true
end

该关联在 Rails 4.2 中运行良好

Property.last.attachments
 Property Load (0.9ms)  SELECT  "accommodations".* FROM "accommodations" WHERE "accommodations"."type" IN ('Property')  ORDER BY "accommodations"."id" DESC LIMIT 1
 Attachment Load (0.5ms)  SELECT "attachments".* FROM "attachments" WHERE "attachments"."attached_item_id" = $1 AND "attachments"."attached_item_type" = $2  [["attached_item_id", 1], ["attached_item_type", "Property"]]

Rails 5.0 中的类似关联

class CustomInquiry < ApplicationRecord;
end

class ChildInquiry < CustomInquiry  
     has_many :text_histories, as: :mailed_item, dependent: :delete_all
end

class TextHistory < ApplicationRecord
    belongs_to :mailed_item, polymorphic: true
end

2.4.0 :002 > ChildInquiry.last.text_histories
 ChildInquiry Load (1.2ms)  SELECT  "custom_inquiries".* FROM "custom_inquiries" WHERE "custom_inquiries"."type" IN ('ChildInquiry') ORDER BY "custom_inquiries"."id" DESC LIMIT $1  [["LIMIT", 1]]
 TextHistory Load (0.4ms)  SELECT "text_histories".* FROM "text_histories" WHERE "text_histories"."mailed_item_id" = $1 AND "text_histories"."mailed_item_type" = $2  [["mailed_item_id", 197], ["mailed_item_type", "CustomInquiry"]]

但是这里的第二个查询应该像这样运行--

 TextHistory Load (0.4ms)  SELECT "text_histories".* FROM "text_histories" WHERE "text_histories"."mailed_item_id" = $1 AND "text_histories"."mailed_item_type" = $2  [["mailed_item_id", 197], ["mailed_item_type", "ChildInquiry"]]

任何人都可以帮助我解决 Rails 5 中的更新内容以及覆盖它的任何猴子补丁。

【问题讨论】：

标签： ruby-on-rails-5 polymorphic-associations sti

【解决方案1】：

最新版本的 ActiveRecord 在关联中使用基类，所以当我们使用 STI 时，它使用基类而不是当前类。因此，为了解决这个问题，您可以使用 Gem gem "store_base_sti_class"。
它将使用 ActiveRecord 关联中的当前类。
这里是github链接

https://github.com/appfolio/store_base_sti_class

【讨论】：