Stripe webhooks – uninitialized constant FulfillCheckout error on Pay::Webhooks.delegator.subscribe

[rameerez]

Hi everyone, I'm following the docs and trying to configure custom Stripe webhook listeners as described here

I add the Pay::Webhooks.delegator.subscribe lines to config/initializers/pay.rb

And then I create a app/webhooks/charge_succeeded.rb file where I put the class FulfillCheckout definition.

However, on rails s, the app crashes with the following error:

Exiting
myapp/config/initializers/pay.rb:1:in `<main>': uninitialized constant FulfillCheckout (NameError)

Pay::Webhooks.delegator.subscribe "stripe.checkout.session.completed", FulfillCheckout.new

I tried adding config.autoload_paths << Rails.root.join('app/webhooks') to config/application.rb in case the custom app/webhooks folder wasn't getting auto-loaded but that doesn't work either – and in any case Zeitwerk should autoload everything under app, right?

As suggested in #486, I also tried this lambda approach:

Pay::Webhooks.delegator.subscribe "stripe.charge.succeeded", ->(event) { FulfillCheckout.new.call(event) }

– but no luck either, same uninitialized constant error.

I've also seen people defining the FulfillCheckout lambda/class itself inside config/initializers/pay.rb as in #517, but that doesn't seem scalable as I start adding more custom webhooks.

Also tried matching the name of the class to the name of the file (charge_succeeded.rb -> class ChargeSucceeded) but I get the exact same error all the time.

It looks like Rails is just not loading my app/webhooks folder – any ideas?

Using ruby 3.2.2 on rails 7.1.2

[deanpcmad]

Your issue is likely due to the file name you've chosen as Zeitwerk, the autoloader that Rails uses, is expecting your charge_succeeded.rb file to have the class ChargeSucceeded

From the Rails docs:

Rails configures Zeitwerk to inflect file names with String#camelize. For example, it expects that app/controllers/users_controller.rb defines the constant UsersController

If you rename the charge_succeeded.rb file to fulfill_checkout.rb, then it will likely work as expected.

[rameerez]

Already tried, doesn't work either. Same error.

[rameerez]

Update: looks like it works if I manually require each file in config/initializers/pay.rb, as in:

require Rails.root.join('app/webhooks/fulfill_checkout.rb')

Pay::Webhooks.delegator.subscribe "stripe.checkout.session.completed", FulfillCheckout.new
Pay::Webhooks.delegator.subscribe "stripe.checkout.session.async_payment_succeeded", FulfillCheckout.new

Not sure this is the best solution, though, since Zeitwerk should be doing this work.

[deanpcmad]

Yeah I was just writing out a comment where I found the same issue in my Pay test app. I did manage to get it to work by prepending Application:: to the FulfillCheckout class but then that stopped working after a few tries 🤔

If you comment it out, the FulfillCheckout class is available in the console, so Zeitwerk is loading it correctly, but it seems that it doesn't load it before the initializers? Very odd.

[deanpcmad]

Also, side note, the PR #943 might be of interest for you which Chris has been working on from discussion #938

[rameerez]

I found out what I was doing wrong: the Pay::Webhooks.delegator.subscribe lines need to go inside an ActiveSupport.on_load(:pay) block, like this:

# config/initializers/pay.rb

ActiveSupport.on_load(:pay) do
  Pay::Webhooks.delegator.subscribe "stripe.checkout.session.completed", FulfillCheckout.new
end

Doing this, there's no need to manually require any files.

Turns out this was not mentioned in the pay docs for Stripe Checkout (docs/stripe/8_stripe_checkout.md) – but it was mentioned in the regular webhooks docs (docs/7_webhooks.md)

Looks like this change was introduced in version 6.4.0 and the Stripe docs were not updated. I'm submitting a PR to fix the Stripe Checkout docs.