Rails单表继承ActiveRecord::SubclassNotFound

Question

我尝试将用户类型更改为“nil”，但现在不断收到此错误消息：

单表继承机制无法定位子类：'nil'。引发此错误的原因是“type”列被保留用于在继承时存储类。如果您不打算将此列用于存储继承类，请重命名该列，或覆盖 User.inheritance_column 以使用另一列来存储该信息。

from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/inheritance.rb:161:in `rescue in find_sti_class'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/inheritance.rb:155:in `find_sti_class'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/inheritance.rb:144:in `discriminate_class_for_record'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/persistence.rb:50:in `instantiate'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/querying.rb:48:in `block in find_by_sql'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/result.rb:55:in `block in each'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/result.rb:55:in `each'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/result.rb:55:in `each'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/querying.rb:48:in `map'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/querying.rb:48:in `find_by_sql'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/relation.rb:603:in `exec_queries'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/relation.rb:487:in `load'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/relation.rb:231:in `to_a'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/bullet-4.13.1/lib/bullet/active_record41.rb:10:in `to_a'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/relation/finder_methods.rb:479:in `find_last'
from /usr/local/rvm/gems/ruby-2.0.0-p481@rails-4.0.2/gems/activerecord-4.1.1/lib/active_record/relation/finder_methods.rb:165:in `last'

我明白为什么会发生这种情况，并且我确实希望发生单表继承，但它甚至不允许我覆盖它 Rails Console。我正在尝试将用户类型更改回我需要的类型，它立即给我该消息。即使我执行 User.find( myID ) 它也不会提取我的数据。

有什么办法我可以告诉它覆盖它并更改类型吗？

编辑：

我试过：

User.last (I was the last user)

User.find(*myId*)

它甚至不让我做User.last.destroyor User.destroy_all，每次在控制台中都会给我同样的错误。

我还尝试创建一个名为“nil”的模型，该模型继承自 User 但仍然没有任何结果。

Answer 1

好吧，你有点搞砸了:)

Rails 的单表继承需要字段中的确切类名type。由于"nil"未指定有效的User子类，因此您创建的对象在 STI 方面没有任何意义。

这很容易修复。选择所有错误条目（包含"nil"在 中type）并修复它们（设置type为nil，这将成为NULL此处表示“基类”的 SQL）：

User.where(type: "nil").update_all(type: nil)