ActionCable lesson: Fix lesson flow for Rails 8 missing channels directory by bittoby · Pull Request #30913 · TheOdinProject/curriculum

bittoby · 2026-03-18T04:55:46Z

Because

Rails 8 no longer auto-generates the app/channels/ directory when running rails new. This causes learners to get stuck when the lesson asks them to open app/channels/application_cable/connection.rb because the file does not exist yet.

This PR

Reorders actioncable_lesson.md so that rails generate channel message runs before editing connection.rb
Updates the expected generator output in both actioncable_lesson.md and websockets_and_actioncable.md to reflect Rails 8 behavior
Removes outdated references to files "already existing" since Rails 8 creates all Action Cable files on first channel generation
Adds a brief note in both lessons explaining that Rails 8 does not generate Action Cable files by default

Issue

Closes #30794

Additional Information

Tested on a fresh Rails 8.1.2 install. Confirmed app/channels/ does not exist after rails new and is properly created after rails generate channel message.

Pull Request Requirements

I have thoroughly read and understand The Odin Project curriculum contributing guide
The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
The Because section summarizes the reason for this PR
The This PR section has a bullet point list describing the changes in this PR
If this PR addresses an open issue, it is linked in the Issue section
If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
If any lesson files are included in this PR, they follow the Layout Style Guide

…s app/channels directory

bittoby · 2026-03-18T05:02:42Z

@JoshDevHub could you please review this PR? Welcome to any feedbacks.
thank you

mao-sz · 2026-03-18T09:16:25Z

@bittoby Please do not ping specific maints for review, especially so soon after opening the PR. We are all volunteers with our own schedules. One of us will eventually get to reviewing this, whether it's Josh or another maintainer.

CouchofTomato · 2026-03-18T14:11:58Z

ruby_on_rails/mailers_advanced_topics/actioncable_lesson.md

 Let's now deal with setting up the server connection. As we covered in the Action Cable lesson, the connection manages all the channels that a client subscribes to and deals with authentication and authorization.

-If you open up `app/channels/application_cable/connection.rb` we can authorise a connection when the user logs in. The code is pretty identical to the [connection](https://guides.rubyonrails.org/action_cable_overview.html#server-side-components-connections) found in the Rails Guides on Action Cable, with the only difference being we can use the user details set on the warden object environment variable.
+In Rails 8, the Action Cable files are not generated by default when you create a new app. We need to generate a channel first, which will also create the necessary Action Cable directory and files. Let's create a channel for messages. In the terminal we can write


Rails 8 has been out for a while now, so we need to specify that this is Rails 8 behaviour. I doubt any learners are still on rails 7. Maybe we could just start with "We need to generate a channel first"

Thanks for your feedback! Fixed

CouchofTomato · 2026-03-18T14:15:39Z

ruby_on_rails/mailers_advanced_topics/actioncable_lesson.md

+
+This has created the Action Cable base files (`connection.rb` and `channel.rb`), as well as the `message_channel.rb` and `message_channel.js` files we will use shortly.
+
+Now open up `app/channels/application_cable/connection.rb` so we can authorize a connection when the user logs in. The code is pretty identical to the [connection](https://guides.rubyonrails.org/action_cable_overview.html#server-side-components-connections) found in the Rails Guides on Action Cable, with the only difference being we can use the user details set on the warden object environment variable.


Will users be familiar with warden?

XAJX179 · 2026-03-18T14:36:02Z

@bittoby Please do not ping specific maints for review, especially so soon after opening the PR. We are all volunteers with our own schedules. One of us will eventually get to reviewing this, whether it's Josh or another maintainer.

hello @mao-sz & @CouchofTomato ,
@statxc was already assigned by josh on this issue as he was the first one to comment #30794 (comment) (on feb 13) on this issue i created. just wanted to share that this PR was created for an issue which has someone else assigned #30794 (comment) (20 hours ago only)

statxc · 2026-03-18T14:40:44Z

Go ahead, @bittoby. I’m working on another issue now, so it’s fine with me.

bittoby · 2026-03-18T14:42:14Z

Go ahead, @bittoby. I’m working on another issue now, so it’s fine with me.

Thanks @statxc 👍

mao-sz · 2026-03-18T14:48:45Z

Good spot @XAJX179, I didn't notice. I'll let Tomato decide what to do with this PR.

@bittoby we have a very clear workflow in place as per our contributing guide, which you ticked the box saying you've read.
When there is an assignment system in place, it is bad etiquette to step over people with your own work. Many teams will simply reject the PR and it wastes everyone's time.

bittoby · 2026-03-18T14:52:42Z

Good spot @XAJX179, I didn't notice. I'll let Tomato decide what to do with this PR.

@bittoby we have a very clear workflow in place as per our contributing guide, which you ticked the box saying you've read. When there is an assignment system in place, it is bad etiquette to step over people with your own work. Many teams will simply reject the PR and it wastes everyone's time.

Ah, thanks for letting me know. By mistaken, I missed that point. Really sorry. I’ll be more careful in the future.
But for this issue, @statxc already agreed that I’m working on it. If possible, I’d like to complete this task. I’ll be more careful going forward. 🙏

bittoby · 2026-03-21T08:27:48Z

I’d appreciate any feedback from anyone.

Fix ActionCable lesson flow for Rails 8 which no longer auto-generate…

eb24ebf

…s app/channels directory

github-actions bot added the Content: Ruby on Rails Involves the Ruby on Rails course label Mar 18, 2026

fix: solve Lint error

c3a7d02

CouchofTomato reviewed Mar 18, 2026

View reviewed changes

fix: update ActionCable lesson

64148a4

bittoby requested a review from CouchofTomato March 18, 2026 15:05

CouchofTomato approved these changes Mar 23, 2026

View reviewed changes

CouchofTomato merged commit 08d025d into TheOdinProject:main Mar 23, 2026
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bittoby deleted the fix/actioncable-missing-channels-rails-8 branch March 23, 2026 21:42

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ActionCable lesson: Fix lesson flow for Rails 8 missing channels directory#30913

ActionCable lesson: Fix lesson flow for Rails 8 missing channels directory#30913
CouchofTomato merged 3 commits intoTheOdinProject:mainfrom
bittoby:fix/actioncable-missing-channels-rails-8

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		This has created the Action Cable base files (`connection.rb` and `channel.rb`), as well as the `message_channel.rb` and `message_channel.js` files we will use shortly.

		Now open up `app/channels/application_cable/connection.rb` so we can authorize a connection when the user logs in. The code is pretty identical to the [connection](https://guides.rubyonrails.org/action_cable_overview.html#server-side-components-connections) found in the Rails Guides on Action Cable, with the only difference being we can use the user details set on the warden object environment variable.

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bittoby commented Mar 18, 2026

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