ruby-on-rails - 单表继承 (STI) 和 has_and_belongs_to_many (HABTM) 关联的错误

Question

使用 Rails 3.0.7，并有以下 4 个模型:

class User < ActiveRecord::Base
end

class Administrator < User
  has_and_belongs_to_many :clients
end

class Client < ActiveRecord::Base
  has_and_belongs_to_many :administrators
  has_and_belongs_to_many :meetings
end

class Meeting < ActiveRecord::Base
  has_and_belongs_to_many :clients

  def self.foo
    self.joins(:clients => :administrators)
  end
end

来电:

Meeting.foo.to_sql

产生:

SELECT meetings.*
FROM meetings
INNER JOIN clients_meetings ON clients_meetings.event_id = meetings.id
INNER JOIN clients ON clients.id = clients_meetings.child_id
INNER JOIN clients_administrators ON clients_administrators.child_id = clients.id
INNER JOIN users ON users.type = 'Administrator'

但似乎错过了“clients_administrators”和“users”之间的最终加入关系。我认为 SQL 的最后一行应该是:

INNER JOIN users ON users.id = clients_administrators.user_id
WHERE users.type = 'Administrator'

这是一个错误吗？还是我误解了什么？

谢谢

Answer 1

这似乎是 bug ，但它已在 Rails 3.1 中解决。