Rails belongs_to association(with:class_name)返回nil

Question

我对Rails开发比较陌生,而且我有一个小的关联问题.我想命名一个与它所链接的模型不同的关联.

我有以下两种型号:

class User < ActiveRecord::Base
  has_many :events
end

class Event < ActiveRecord::Base
  belongs_to :admin, :class_name => "User" # So we can call event.admin to retrieve the User who owns this Event
end

我建立一个用户如下:

event = event.create! :title => "New Event"

user = User.create! :username => "thinkswan"
user.events << event
user.save

当我跳进控制台时,我收到以下信息:

irb> user = User.find(1)
irb> user.events
=> [#<Event id: 1, title: "New Event", user_id: 1, created_at: "2011-06-09 06:41:09", updated_at: "2011-06-09 06:41:10">]

irb> event = Event.find(1)
irb> event.user_id
=> 1
irb> event.admin
=> nil

任何人都可以解释为什么该admin关联没有返回它指向的用户？谢谢!

Answer 1

您需要同时指定:class_name和:foreign_key,例如:

belongs_to :admin, :class_name => "User", :foreign_key => "user_id"