与同一模型的多个has_one关系

Question

我有一个User和一个Shop模型（Rails 5.2）应该有多个位置，如ship_location，bill_location ...我怎么能多次使用相同的Location？

User和Shop模型可能看起来像这样

class User
  has_one :ship_location
  has_one :bill_location
end

class Shop
  has_one :ship_location
  has_one :bill_location
  has_one :contact_location
end

但我无法弄清楚Location模型应该是什么样子。它应该尽可能抽象，因此当Location用于另一个模型时，我不必定义新的关系和/或模型。

我想我必须使用某种多态性：

class Location
  # location has owner_id and owner_type
  belongs_to :owner, polymorphic: true
end

但这不起作用，因为user.ship_location是模糊的（它会寻找owner_type == "User"和owner_id == 1，但因为还有一个bill_location与owner_type和owner_id相同，它不起作用）。

我是否需要为此创建单独的模型，它们共享同一个表？

Answer 1

1 =>在location_type模型中取一列（让我们说shipping location或任何可以在billing location，contact location和Location之间产生差异的列）

class User
  has_one :ship_location, -> { where("location_type = ?", 'ship') }, :class_name => "Location", :dependent => :destroy
  has_one :bill_location, -> { where("location_type = ?", 'bill') }, :class_name => "Location", :dependent => :destroy
end

class Shop
  has_one :ship_location, -> { where("location_type = ?", 'ship') }, :class_name => "Location", :dependent => :destroy
  has_one :bill_location, -> { where("location_type = ?", 'bill') }, :class_name => "Location", :dependent => :destroy
  has_one :contact_location, -> { where("location_type = ?", 'contact') }, :class_name => "Location", :dependent => :destroy
end

class Location
  belongs_to :user
  belongs_to :shop
  # (has column 'location_type')
end

2 =>创建位置时提供它各自的值（即ship，bill，contact）示例 - >让我们说为location = loation_type创建bill

Location.create(location_type: 'ship', foo: 'bar' ...)