Rails：这些模型的正确关联是什么？

Question

这个问题的正确关联是什么？

共有三种型号：

• 居民
• 各方
• 地址

每个Resident 和Party 都有一个Address

每个Address 可以属于Resident 或Party 或两者。

可以有多个Parties在同一个Address和多个Residents住在那个位置。

habtm 关系是这些模型的最佳解决方案吗？

我打算进行多态关联，但由于Address 可能同时属于Resident 和Party 多次，因此出现了冲突

---

我希望能够做...之类的事情

address = Address.find_or_create_by_street("100 Some Street")

# Associate the Party with a specific Address:
party_object.address = address

# Find all Parties happening at a specific Address:
address.parties do ...

# Find all Residents located at a specific Address:
address.residents.each do ...

---

运行 Rails 3 + MySQL 5.5

Answer 1

我认为不需要多态性

class Address < ActiveRecord::Base
  has_many :parties
  has_many :residents
end

class Party < ActiveRecord::Base
  belongs_to :address
end

class Resident < ActiveRecord::Base
  belongs_to :address
end

 # Address can have multiple parties, and multiple residents. 
 # Resident belongs to an address (lives at only 1 address). 
 # A party belongs to an address (party can be only at 1 address).

address = Address.create(:name => "10 something street.")
address.parties << Party.create(:name => "first")
address.parties << Party.create(:name => "second")
address.residents << Resident.create(:name => "John")
address.residents << Resident.create(:name => "Jane")


Party.first.address.name #10 something street.
Resident.first.address.name #10 something street.
address.parties.size #2
address.residents.size #2

Resident.first.address.parties.size #2

Answer 2

Rails 专家似乎正在逐步停止使用 habtm。我认为您可以通过简单的 has_many 来做到这一点：

class Resident < ActiveRecord::Base
  belongs_to :address
end

class Party < ActiveRecord::Base
  belongs_to :address
end

class Address < ActiveRecord::Base
  has_many :residents 
  has_many :parties
end

从这些关联中，您可以执行以下操作

party.address
address.residents
address.parties
party.address.residents
resident.address.parties

架构

与此相关的 SQL 模式（省略 Rails 默认值）如下所示：

create_table "residents" do |t|
  t.integer  "address_id"
  t.string   "name"
  ... etc
end

create_table "parties" do |t|
  t.integer  "address_id"
  t.datetime "start_time"
  ... etc.
end

create_table "addresses" do |t|
  t.string   "first_line"
  ...etc.
end

编辑 按照@klochner 的正确建议，更新了 :has_one -> :belongs_to 关于居民和各方的信息。