Question

是否可能有多态＆＃34; has_many＆＃34;铁路协会？

我有一张notifications的表communication_method，可以是电子邮件地址或电话号码：

change_table :notifications do |t|
  t.references :communication_method, :polymorphic => true
end

class Notification < ActiveRecord::Base
  belongs_to :communication_method, :polymorphic => true
  belongs_to :email_address, foreign_key: 'communication_method_id'
  belongs_to :phone_number, foreign_key: 'communication_method_id'
end

module CommunicationMethod
  def self.included(base)
    base.instance_eval do
      has_many :notifications, :as => :communication_method, :inverse_of => :communication_method, :dependent => :destroy
    end
  end
end

class EmailAddress
  include CommunicationMethod
end

class PhoneNumber
  include CommunicationMethod
end

现在我希望每个通知都有多种通信方式，是否可能？（类似于has_many :communication_methods, :polymorphic => true）我想我还需要在oder中进行迁移，以便为通信方法创建多对多的通知表

Answer 1

据我所知，Rails仍然不支持多态has_many关联。我正在解决这个添加新的中间模型，它具有多态关联。对于您的情况，它可能如下所示：

class Notification < ActiveRecord::Base
  has_many :communication_method_links
  has_many :email_communication_methods, :through => :communication_method_links, :class_name => 'EmailAddress'
  has_many :email_communication_methods, :through => :communication_method_links, :class_name => 'PhoneNumber'
  belongs_to :email_address, foreign_key: 'communication_method_id'
  belongs_to :phone_number, foreign_key: 'communication_method_id'
end

class CommunicationMethodLink < ActiveRecord::Base
  belongs_to :notification
  belongs_to :communication_methods, :polymorphic => true
end

module CommunicationMethod
  def self.included(base)
    base.instance_eval do
      has_many :communication_method_links, :as => :communication_method, :inverse_of => :communication_method, :dependent => :destroy
    end
  end
end

class EmailAddress
  include CommunicationMethod
end

class PhoneNumber
  include CommunicationMethod
end

因此，CommunicationMethodLink的迁移将如下所示：

create_table :communication_method_links do |t|
  t.references :notification
  t.references :communication_method, :polymorphic => true
end

rails polymorphic has_many association

1 个答案: