Rails 单表继承 - 显式设置类型的最佳方法是什么? [英] Rails Single Table Inheritance - What is the best way to explicitly set type?

问题描述

我在 Rails 应用程序中使用 单表继承，并且想要显式设置实例的类型.

I am using single table inheritance in my rails application, and want to explicitly set the type of an instance.

我有以下内容；

class Event < ActiveRecord::Base
class SpecialEvent < Event

通过单表继承实现.

SpecialEvent.new 按预期工作，但我希望能够执行类似

SpecialEvent.new works as expected, but I want to be able to do things like

Event.new(:type => 'SpecialEvent')

因此我可以在应用程序中轻松创建不同的子类型.

So I can create different sub_types easily in the application.

但是这不起作用，似乎将 :type 设置为 nil，而不是我设置的值；我怀疑这是因为通过调用 Event.new 它覆盖了 :type 参数.

However this doesn't work and seems to set :type to nil, not the value I set it to; I suspect this is because by calling Event.new it is overwriting the :type argument.

有没有人有这样做的好方法?

Has anyone got a good way of doing this?

推荐答案

如果您尝试动态实例化一个子类型，并且您将该类型作为字符串，您可以这样做:

If you're trying to dynamically instantiate a subtype, and you have the type as a string, you can do this:

'SpecialEvent'.constantize.new()

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