Question

我已将我的模型定义如下。我正在尝试@user.orders使用has_many。我已经定义了一个方法：orders来显示我想要的行为。

class Location < ActiveRecord::Base
  belongs_to :locationable, polymorphic: true
  has_many :orders, ->(location) { where(location.locationable_type == 'User') }, class_name: 'Order', foreign_key: :drop_location_id
  # but this does not check for type
  # it produces the SQL: SELECT "orders".* FROM "orders" WHERE "orders"."drop_location_id" = $1
end

class Order < ActiveRecord::Base
  # location is polymorphic, so type of location can be merchant/user
  belongs_to :pickup_location, class_name: 'Location'
  belongs_to :drop_location, class_name: 'Location'
end

class User < ActiveRecord::Base
  has_many :locations, as: :locationable

  # TODO: make it a has_many :orders instead
  def orders
    Order.where(drop_location: locations)
  end
end

使用方法并不像 rails方式。此外，我希望它与rails_admin一起使用。

Answer 1

到目前为止，您应该收到一条错误消息，表明您无法通过多态关联使用has_many。如果你考虑它，它是完全合理的，你的ORM（ActiveRecord）如何形成查询，因为连接将是可怕的。

如何设置一个有很多：通过＆＃39;多态关联

1 个答案: