This post originated from an RSS feed registered with Ruby Buzz by Ryan Davis. Original Post: STI and Abstract Classes Driving You Nuts? Feed Title: Polishing Ruby Feed URL: http://blog.zenspider.com/index.rdf Feed Description: Musings on Ruby and the Ruby Community... Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Ryan Davis Latest Posts From Polishing Ruby

If you happen to be hit by Ticket #5704: Bug in ActiveRecord::Base when mixing STI and abstract models, and you're seeing failures to find STI instances intermittently in development mode, try the following:

class MyAbstractModel < ActiveRecard::Base
  self.abstract_class = false
  # ...
end

-----

class MySTIModel < MyAbstractModel
  TYPES = %w(sub1 sub2 sub3)
  def self.inherited(cls)
    super
    raise "not in #{self.class}::TYPES: #{cls}" unless TYPES.include? cls.name.downcase
  end
end

MySTIModel::TYPES.each do |f|
  require_dependency f
end

-----

class Sub1 < MySTIModel; end
class Sub2 < MySTIModel; end
class Sub3 < MySTIModel; end

It is a stupid bug and I can't do much about it, but the above workaround seems to be a nice tradeoff between horrible hack and maintainability. By pushing the list of subclasses up to the TYPES array, you keep it visible and near the top of the file. By having the inherited hook, you keep slipups in maintainability as visible as possible.