Question

我想做一些看似简单的联想：

class OrderWizard < ActiveRecord::Base
  belongs_to :buyer_wizard,     :class_name => MiniWizard.name
  belongs_to :seller_wizard,    :class_name => MiniWizard.name
end

class MiniWizard < ActiveRecord::Base
   has_one :order_wizard, :foreign_key = '????' # Could be buyer_wizard_id or seller_wizard_id

   def is_buyer_wizard?
     ??
   end

   def is_seller_wizard?
     ??
   end
end

相关的MiniWizard需要知道谁正在连接它。假设has_many：通过最好的方式去？如果是这样，模型将如何看待？
MiniWizard实例需要知道它是买方还是卖方。坚持如何做到这一点。

Answer 1

你实际上可能想要两个关联，例如，这样的事情可能更准确地代表关系：

class MiniWizard < ActiveRecord::Base
   has_one :bought_order_wizard, :foreign_key => 'buyer_wizard_id', :class_name => 'MiniWizard'
   has_one :sold_order_wizard, :foreign_key => 'seller_wizard_id', :class_name => 'MiniWizard'

  def order_wizard
    bought_order_wizard || sold_order_wizard
  end

  def is_buyer_wizard?
    !bought_order_wizard.nil?
  end

  def is_seller_wizard?
    !sold_order_wizard.nil?
  end
end

具有多个潜在外键的同一表中的多个关联

1 个答案: