我有3个型号,用户,连接,可疑

用户有很多连接,
Connection有一个Suspect,通过case_id链接

用户通过其连接有许多嫌疑人.

代码如下：

class User < ActiveRecord::Base
  has_many :followers
  has_many :suspects,:through => :followers
end

class Connection < ActiveRecord::Base
  belongs_to :user
  belongs_to :suspect,:primary_key => :case_id,:foreign_key => :case_id
end

class Suspect < ActiveRecord::Base
  belongs_to :connection,:foreign_key => :case_id
end

问题是belongs_to似乎忽略了：主键.

如果我做

u = User.find(:first)
u.suspects

生成的sql是：

SELECT `suspects`.* FROM `suspects` INNER JOIN `connections` ON `suspects`.id = `connections`.case_id WHERE ((`followers`.user_id = 1))

但它应该是：

SELECT `suspects`.* FROM `suspects` INNER JOIN `connections` ON `suspects`.case_id = `connections`.case_id WHERE ((`followers`.user_id = 1))

有人能指出我正确的方向吗？

詹姆士