Question

我是Ruby on Rails的新手，我正试图模拟我的表关系。

为了简化问题，假设我有3个表：
- 客户（id，address_id，...）
- 员工（id，address_id，...）
- 地址（id，...）

地址模型是否具有以下内容？

has_one :customer
has_one :employee

我知道在单一关系的情况下这是正确的，但我找不到任何有这样的“has_one”关系的例子。

Answer 1

您应该使用多态关联，如下所示。

# Address model
class Address < ActiveRecord::Base
  belongs_to :addressable, :polymorphic => true
end

# Customer model
class Customer < ActiveRecord::Base
  has_one :address, :as => :addressable
end

# Employee model
class Employee < ActiveRecord::Base
  has_one :address, :as => :addressable
end

# Migration script for `addresses` table
class CreateAddresses < ActiveRecord::Migration
  def self.up
    create_table :addresses, :force => true do |t|
      t.references :addressable, :polymorphic => true, :null => false

      # add other address fields

      t.timestamps      
    end

    add_index :addresses, ["addressable_id", "addressable_type"], :name => "fk_addressable"

end

现在您可以执行以下操作：

customer = Customer.new
customer.address = Address.new(:street => "ABC", :city => "SF", :zip => "46646")
customer.save

OR

employee = Employee.last
print employee.address.street

Ruby on Rails ActiveRecord：在多个其他表中包含外键的表

1 个答案: