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ruby-on-rails - 用不同的外键定义 has_one

问题描述

我有两个 Rails 模型，Hub和Advisor. 一个Hubhas_manyAdvisor就像这样：

class Hub < ApplicationRecord
  has_many :advisors
end

我想设置一个特别Advisor的人作为该中心的经理。我已经manager_id像这样向集线器添加了一个：

class AddManagerToHub < ActiveRecord::Migration[5.1]
  def change
    change_table :hubs do |t|
      t.references :manager, references: :advisors
    end
  end
end

但我无法弄清楚在模型中设置这种关系的正确咒语。逻辑会规定它应该是：

has_one :manager, class_name: 'Advisor', primary_key: :manager_id

但是当我这样保存时：

hub.manager = advisor
hub.save

集线器 ID 未设置。是什么赋予了？

Hubs表的表结构为：

Column      |        Type         | Collation | Nullable |             Default              | Storage  | Stats target | Description 
------------------+---------------------+-----------+----------+----------------------------------+----------+--------------+-------------
id               | bigint              |           | not null | nextval('hubs_id_seq'::regclass) | plain    |              | 
name             | character varying   |           |          |                                  | extended |              | 
address_line_1   | character varying   |           |          |                                  | extended |              | 
address_line_2   | character varying   |           |          |                                  | extended |              | 
postcode         | character varying   |           |          |                                  | extended |              | 
longitude        | double precision    |           |          |                                  | plain    |              | 
latitude         | double precision    |           |          |                                  | plain    |              | 
ward_mapit_codes | character varying[] |           |          | '{}'::character varying[]        | extended |              | 
manager_id       | bigint              |           |          |                                  | plain    |              | 
Indexes:
"hubs_pkey" PRIMARY KEY, btree (id)
"index_hubs_on_manager_id" btree (manager_id)
Referenced by:
TABLE "advisors" CONSTRAINT "fk_rails_d86df62174" FOREIGN KEY (hub_id) REFERENCES hubs(id)

标签： ruby-on-railsactiverecord

解决方案

由于manager_id在集线器中添加了对Advisorso 关联的引用应该是这样的：-

class Hub < ApplicationRecord
  has_many :advisors
  belongs_to  :hub_manager, class_name => "Advisor", :foreign_key => "manager_id", optional: true
end

class Advisor < ApplicationRecord
  belongs_to :hub
  has_many :owned_hubs, class_name => "Hub", :foreign_key => "manager_id",
end

查询将如下所示： -

hub.hub_manager = advisor
hub.save

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