Question

此问题的正确关联是什么？

有三种型号：

居民
缔约方
地址

每个Resident和Party都有一个Address

每个Address都可以属于Resident或Party或两者。

同一Parties位置可能有多个Address，而位于该位置的多个Residents。

habtm 关系是这些模型的最佳解决方案吗？

我考虑过做多态关联但是出现了冲突，因为Address可能同时属于Resident和Party

我希望能够做到......

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大师似乎正逐步停止使用habtm。我认为你可以用一个简单的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

从这些协会中你可以做一些事情，比如

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

<强>模式

与此类似的SQL模式（省略Rails默认值）看起来像：

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

EDIT 更新：has_one - ＆gt; ：@klochner正确建议的居民和当事人的belongs_to。

Rails：这些模型的正确关联是什么？

2 个答案: