Rails has_many：through - >如何设置关联以从多个连接模型中拉取？

Question

我想设置多个has_many：通过并行关系。这里是我的2个标准和2个连接模型：

User.rb

has_many :ownerships, dependent: :destroy 
has_many :devices, through: :ownerships 

has_many :bookings, dependent: :destroy 
has_many :devices, through: :bookings 

Ownership.rb

belongs_to :user, touch: true, counter_cache: :devices_count 
belongs_to :device, touch: true 

Booking.rb

belongs_to :user, touch: true, counter_cache: :bookings_count 
belongs_to :device, touch: true, counter_cache: :bookings_count 

Device.rb

has_many :ownerships, dependent: :destroy 
has_many :users, through: :ownerships 

has_many :bookings, dependent: :destroy 
has_many :users, through: :bookings 

预期该电流设置不工作，似乎是加盟模式之间的串扰。我希望连接模型能够独立并行（即用户可以拥有关系 - 所有权 - 设备无法预订）。我不在这里寻找嵌套的has_many：through关系。

当我更改设备的用户所有权似乎改变了预订的数量，反之亦然......我应该如何正确设置它的任何想法？

Answer 1

我想你已经得到了第一个错误是你同名调用两个协会（users/devices）

帮助任何进一步的受访者中，真正的问题是 - >how do you set up an association to pull from multiple join models?

---

快速修复

的Rails协会按其类为主命名，但BEC冲突的使用，你应该避免设置它们两次。这就是你看到当前问题的原因。一个简单的分辨率会用不同的名字来调用关联：

User.rb 
has_many :ownerships, dependent: :destroy 
has_many :owner_devices, through: :ownerships, class_name: "Device", foreign_key: "ownership_id" 

has_many :bookings, dependent: :destroy 
has_many :booking_devices, through: :ownerships, class_name: "Device", foreign_key: "booking_id" 

我仍然在寻找的信息，你怎么可以设置关联使用两个模型

Answer 2

这似乎是一个可行的解决方案如下丰富佩克建议：

User.rb

has_many :ownerships, dependent: :destroy 
has_many :device_ownerships, through: :ownerships, class_name: "Device", foreign_key: "device_id", source: :device 

has_many :bookings, dependent: :destroy 
has_many :device_bookings, through: :bookings, class_name: "Device", foreign_key: "device_id", source: :device 

Booking.rb（加入模型）

belongs_to :user, touch: true, counter_cache: :bookings_count 
belongs_to :device, touch: true, counter_cache: :bookings_count 

Ownership.rb（加入模型）

belongs_to :user, touch: true, counter_cache: :devices_count 
belongs_to :device, touch: true, counter_cache: :users_count 

设备。RB

has_many :ownerships, dependent: :destroy 
has_many :user_ownerships, through: :ownerships, class_name: "User", foreign_key: "user_id", source: :user 

has_many :bookings, dependent: :destroy 
has_many :user_bookings, through: :bookings, class_name: "User", foreign_key: "user_id", source: :user 

说实话，我在为什么foreign_key的需要（？）被设置为他们有点糊涂了，所以我必须做更多的阅读了。否则它看起来是功能性的，我没有看到这些连接模型之间的串扰了。