Rails：无法使用 STI 加载表的固定装置（未定义的方法“reflect_on_all_associations”）

Question

我无法为使用 STI 的桌子加载装置。

当我调用 FIXTURES=schools rake db:fixtures:load 时，出现此错误：

undefined method `reflect_on_all_associations' for Object:Class

• 其他装置加载正常，即 FIXTURES=committes rake db:fixtures:load
• 装置是通过调用rake db:fixtures:extract创建

这是我的学校迁移：

class CreateSchools < ActiveRecord::Migration
  def self.up
    create_table :schools do |t|
      t.string :name
      t.string :type
      t.string :street
      t.string :city
      t.string :province
      t.timestamps
    end
  end
...
end

我有一些模型文件，即school.rb：

class School < ActiveRecord::Base
end

和secondary_school.rb：

class SecondarySchool < School
end

这是堆栈跟踪：

undefined method `reflect_on_all_associations' for Object:Class
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:597:in `insert_fixtures'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:568:in `each'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:568:in `insert_fixtures'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:512:in `create_fixtures'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:512:in `each'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:512:in `create_fixtures'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in `transaction'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:510:in `create_fixtures'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/connection_adapters/mysql_adapter.rb:267:in `disable_referential_integrity'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:501:in `create_fixtures'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/base.rb:1482:in `silence'
/home/loranaw/ruby/gems/gems/activerecord-2.3.10/lib/active_record/fixtures.rb:500:in `create_fixtures'
/home/loranaw/ruby/gems/gems/rails-2.3.10/lib/tasks/databases.rake:223
/home/loranaw/ruby/gems/gems/rails-2.3.10/lib/tasks/databases.rake:222:in `each'
/home/loranaw/ruby/gems/gems/rails-2.3.10/lib/tasks/databases.rake:222

以及一些示例 YML：

--- 
schools_7133: 
  city: Nahanni Butte
  name: Charles Yohin School
  created_at: 2010-11-26 02:36:39
  grade_range: K-10
  latitude: "61.03349"
  country: CA
  updated_at: 0000-00-00 00:00:00
  postal_code: "X0E 0N0"
  url: 
  street: ""
  id: "9682"
  type: SecondarySchool
  fax: (867) 602-2202
  phone: (867) 602-2200
  funding: 
  longitude: "-123.38642"
  school_type: 
  province: NT
  email: 

Answer 1

School 对象有一个名为 type 的字段，该字段是为单表继承保留的。重命名该字段应该可以解决问题。

Answer 2

问题最终是其中一条记录的类型值为空白/空。确保 STI 表中的每一行都有一个类型。