Descendants tracking error when `cache_classes = true`

[mockdeep]

We're getting an error when we have cache_classes = true on CI with Rails 7.0.1:

 RuntimeError:
              DescendantsTracker.clear was disabled because config.cache_classes = true
            # /home/circleci/app/vendor/bundle/ruby/2.7.0/gems/activesupport-7.0.1/lib/active_support/descendants_tracker.rb:119:in `clear'
            # /home/circleci/app/vendor/bundle/ruby/2.7.0/gems/with_model-2.1.6/lib/with_model/model.rb:59:in `cleanup_descendants_tracking'
            # /home/circleci/app/vendor/bundle/ruby/2.7.0/gems/with_model-2.1.6/lib/with_model/model.rb:38:in `destroy'
            # /home/circleci/app/vendor/bundle/ruby/2.7.0/gems/with_model-2.1.6/lib/with_model.rb:53:in `block in setup_object'

[airblade]

Me too. config.cache_classes = true is the default in Rails 7.

[maestromac]

Same here.

[waiting-for-dev]

See https://guides.rubyonrails.org/upgrading_ruby_on_rails.html#upgrading-from-rails-6-1-to-rails-7-0-spring. It needs to be explicitly set to false from Rails 7 when Spring is not used.

[airblade]

@waiting-for-dev I read that the opposite way, i.e. it needs to be set to false in Rails 7 when Spring is used.

[waiting-for-dev]

@waiting-for-dev I read that the opposite way, i.e. it needs to be set to false in Rails 7 when Spring is used.

Yeah, that wording is confusing. See here instead https://guides.rubyonrails.org/configuring.html#config-cache-classes

[airblade]

That's much clearer, thanks.

[waiting-for-dev]

@airblade, in the end, I think you're right. It should be true in the test environment, and it should only be false when Spring is present, as it'll handle cache by itself. So, yeah, I think this should be fixed from with_model end.

[Benoit-Baumann]

I have the same error with Rails 7.0.2 and the new default config.cache_classes = true.

Any chance to have this issue fixed @nertzy ?

[stex]

It doesn't fix the actual issue, but I added a local monkey-patch to get with_model running with Rails 7, maybe it's of use to someone else.

# spec/support/with_model.rb

module WithModel
  class Model
    # Workaround for https://github.com/Casecommons/with_model/issues/35
    def cleanup_descendants_tracking
      if defined?(ActiveSupport::DescendantsTracker) && !Rails.application.config.cache_classes
        ActiveSupport::DescendantsTracker.clear([@model])
      elsif @model.superclass.respond_to?(:direct_descendants)
        @model.superclass.subclasses.delete(@model)
      end
    end
  end
end

[Benoit-Baumann]

Thanks for the workaround @Stex !

[nertzy]

Does #44 fix this issue?

[Benoit-Baumann]

Unfortunately no, I still get the same error... Stex's workaround works like a charm, though.

[swishstache]

@nertzy is there a chance of some variant of @stex 's fix above being incorporated into a future release? I'm not sure what he means by "... doesn't fix the actual issue... ". It would appear calling ActiveSupport::DescendantsTracker.clear under Rails >= 7 with config.cache_classes set to true (the default for the test environment) will no longer work. What else could we do other than delete from subclasses?

For those looking, here's the commit to 7.0.0 that is the root of this: https://github.com/rails/rails/commit/cb82f5f0a438c7be64ca1c0633556f6a535138b6

[markedmondson]

Hey @nertzy if you're happy to add me as an owner on Rubygems I can get this out.