通过四个模特有关系吗？

Question

我在模型之间建立这种关联时遇到问题。

一个用户有多个住宿，而住宿有一个用户。

住宿有许多通知，而通知有一种住宿。

请求有很多通知。

我怎样才能获得给定用户的所有请求（即用户 -> 住宿（每个） -> 通知 -> 请求）？

更新：

这是我当前的控制器文件：

class PanelController < ApplicationController

  before_filter :login_required

  def index
    @accommodations = current_user.accommodations.all
    @requests = Array.new
    @accommodations.each do |a|
      a.notifications.each do |n|
        @requests << Request.where('id' => n.request_id)
      end
    end

  end

end

和模型：

models/user.rb

class User < ActiveRecord::Base
  [snip]
  has_many :accommodations
  has_many :notifications,
           :through => :accommodations
end

models/accommodation.rb

class Accommodation < ActiveRecord::Base
  validates_presence_of :title, :description, :thing, :location, :spaces, :price, :photo
  attr_accessible :photo_attributes, :title, :description, :thing, :location, :spaces, :price
  has_one :photo
  has_many :notifications
  belongs_to :user
  accepts_nested_attributes_for :photo, :allow_destroy => true
end

models/notification.rb

class Notification < ActiveRecord::Base
  attr_accessible :accommodation_id, :request_id
  has_one :request
  belongs_to :accommodation
end

模型/request.rb

class Request < ActiveRecord::Base
  belongs_to :notifications
  attr_accessible :firstname, :lastname, :email, :phone, :datestart, :dateend, :adults, :children, :location, :status
  validates_presence_of :firstname, :lastname, :email, :phone, :datestart, :dateend, :children, :adults, :location
end

Answer 1

像这样的东西应该有效：

@reqs = []    
@user.accommodations.all.each do |a|
    @reqs << a.notification.request
end

假设这是正确的：

class User
    has_many :accommodations
end

class Accommodation
    belongs_to :user
    has_many :notifications
end

class Notification
    belongs_to :accomodation
    belongs_to :request
end

class Request
    has_many :notifications
end

---

使用 has_many :through 不适用于多个模型，如下所示：Ruby-on-Rails: 多个 has_many :through 可能吗？

但是你可以在你的用户模型中做这样的事情：

class User
    has_many :accommodations
    has_many :notifications,
             :through => :accommodations

    def requests 
        self.notifications.all.collect{|n| n.request }
    end
end