破壞belongs_to的離開FK

Question

我有一個模型：

class Merchant < ActiveRecord::Base 
    belongs_to :billing_address, class_name: Address, dependent: :destroy 
    belongs_to :other_address1, class_name: Address, dependent: :destroy 
    belongs_to :other_address2, class_name: Address, dependent: :destroy 
    belongs_to :other_address3, class_name: Address, dependent: :destroy 
    belongs_to :other_address4, class_name: Address, dependent: :destroy 
    ... 
end 

Address沒有關聯。

當我這樣做：

merchant.billing_address.destroy 

在數據庫中，該地址記錄了，但merchants.billing_address_id保持一個假值。這是mysql，所以沒有參照完整性。

我在做什麼錯？

注意：我知道這可能更好地模擬爲has_one關聯。我可能不得不去那裏，但我寧願不去。

更新：增加了一些代碼來顯示多個地址關聯。

Answer 1

原來，ActiveRecord不支持單向belongs_to關聯，unlike other ORMs I've worked with。但是你可以自己破解它，像這樣：

before_save :remove_ids_for_nil_associations 

def remove_ids_for_nil_associations 
    self.billing_address_id = nil if is_getting_destroyed? self.billing_address 
    ... 
end 

def is_getting_destroyed?(ref) 
    ref.present? && ref.destroyed? 
end 

Answer 2

如果你想merchant.billing_address給你破壞了帳單地址後爲空，那麼你需要在地址模型使用:dependent => :nullify。

參考號http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html