ruby-on-rails - 如何在 Rails 中通过继承获得多态关系？

Question

我有以下 rails 模型。

class Service < ApplicationRecord
  self.table_name ='service'
end

class ChildA < Service
  has_many :charges
end

class ChildB < Service
  self.table_name = "childb_table"
  has_many :charges
end

class Charges < ApplicationRecord
  :belongs_to chargeable, polymorphic: true
end
# code using this
a = ClassB.new.save
charge = Charges.new.save
a.charges.add(a) # this adds the column with the class name 'Service'

我尝试保存对象，但 chargeable_type 字段始终设置为基类 service 而不是子类。

我该如何解决这个问题？

Answer 1

您可以将 Service 类定义为抽象类。

使用 Rails 5.1 进行测试

class Service < ApplicationRecord
  self.table_name ='service'
  self.abstract_class = true
end

示例来自:http://www.rubydoc.info/docs/rails/4.0.0/ActiveRecord%2FInheritance%2FClassMethods%3Aabstract_class

class SuperClass < ActiveRecord::Base
  self.abstract_class = true
end

class Child < SuperClass
  self.table_name = 'the_table_i_really_want'
end