Get a list/array of child classes from Single Table Inheritance in Rails?

ruby-on-rails single-table-inheritance
thoughtpunch picture thoughtpunch · May 10, 2012 · Viewed 10.1k times · Source

I have a whole bunch of child classes that inherit from a parent class via single-table-inheritance in my Rails app. I'd like a way to get an array of all the child classes that inherit from the main class.

I tried the following single-link command that I found in another SO answer, but it only returns the parent class.

ObjectSpace.each_object(class<<MyParentClass;self;end)

Is there any clean way to do this?

EDIT: Apparently Rails only lazy-loads child classes when called in Dev mode, and possibly production depending on the Rails version. However, the first answer should work on Rails 3.1 and higher in Prod mode.

Answer

Pavling picture Pavling · May 10, 2012

Rails extends Ruby Class with the subclasses() method.

In Rails 3 you can call it directly:

YourClass.subclasses

In Rails 2.3, ".subclasses" is protected, so we use have to call it using send():

YourClass.send(:subclasses)

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