Question

当我访问模型＆＃39;位置＆＃39;以两种不同的方式，我得到了两个不同版本的模型。

其中一个人有location_id: nil，其中一人有location_id: 3

2.0.0-p481 :054 > e.shifts.last.location
 => #<Location id: 35, location_id: 3, name: "Hoxton Hotel", address_1: "81 Great Eastern St", postcode: "EC2A 3HU", lng: -0.0827515, lat: 51.5256224, locatable_id: 13, locatable_type: "Shift", created_at: "2015-09-10 09:59:55", updated_at: "2015-09-11 10:18:41", radius: 5.0> 

2.0.0-p481 :052 > Location.find(35)
  Location Load (0.8ms)  SELECT  "locations".* FROM "locations" WHERE "locations"."id" = $1 LIMIT 1  [["id", 35]]
 => #<Location id: 35, location_id: nil, name: "Hoxton Hotel", address_1: "81 Great Eastern St", postcode: "EC2A 3HU", lng: -0.0827515, lat: 51.5256224, locatable_id: 13, locatable_type: "Shift", created_at: "2015-09-10 09:59:55", updated_at: "2015-09-11 10:18:41", radius: 5.0>

该模型具有这种自我指涉关联：

has_many :children, class_name: "Location", foreign_key: "location_id", dependent: :nullify
belongs_to :parent, class_name: "Location", foreign_key: "location_id"

问题是当我做Location.find（3）.children时，并非所有的孩子都会回来。

Answer 1

我认为ActiveRecord在外键的名称上行为不正确。也许您可以尝试更好地命名关联，例如parent

has_many :children, class_name: "Location", foreign_key: "parent_id", dependent: :nullify
belongs_to :parent, class_name: "Location", foreign_key: "parent_id"

顺便问一下，e.shifts是什么？您可以尝试使用您的模型，现在可以Location.last查看结果是否相同？

Answer 2

这是因为在多个：one关系中，关系id位于'one'端，因为它是作为基础表上的一种外键实现的。

我认为你可能想要一个自我引用很多：很多关系，这是通过一个加入关系来实现的，它实现为一个带有id关系的表。

class Location < ActiveRecord::Base
   has_many :location_relationships, :foreign_key => "child_id", :class_name => "LocationRelationship"
   has_many :children, :through => :location_relationships
end

class LocationRelationship < ActiveRecord::Base
   belongs_to :location, :foreign_key => "location_id", :class_name => "Location"
   belongs_to :child, :foreign_key => "child_id", :class_name => "Location"  
end

如果访问方式不同，请获取相同型号的不同版本

2 个答案: