Action Cable Patterns for Rails 8

Overview

Action Cable integrates WebSockets with Rails:

• Real-time updates without polling

• Server-to-client push notifications

• Chat and messaging features

• Live dashboards and feeds

• Collaborative editing

Quick Start

Action Cable is included in Rails by default. Configure it:

config/cable.yml

development: adapter: async

test: adapter: test

production: adapter: solid_cable # Rails 8 default

OR

adapter: redis url: <%= ENV.fetch("REDIS_URL") %>

Project Structure

app/ ├── channels/ │ ├── application_cable/ │ │ ├── connection.rb # Authentication │ │ └── channel.rb # Base channel │ ├── notifications_channel.rb │ ├── events_channel.rb │ └── chat_channel.rb ├── javascript/ │ └── channels/ │ ├── consumer.js │ ├── notifications_channel.js │ └── events_channel.js spec/channels/ ├── notifications_channel_spec.rb └── events_channel_spec.rb

Connection Authentication

app/channels/application_cable/connection.rb

module ApplicationCable class Connection < ActionCable::Connection::Base identified_by :current_user

def connect
  self.current_user = find_verified_user
end

private

def find_verified_user
  # Using Rails 8 authentication
  if session_token = cookies.signed[:session_token]
    if session = Session.find_by(token: session_token)
      session.user
    else
      reject_unauthorized_connection
    end
  else
    reject_unauthorized_connection
  end
end

end end

Channel Patterns

Four core patterns are available. See channel-patterns.md for full Ruby and JavaScript implementations:

• Pattern 1: Notifications Channel — streams per-user notifications via stream_for current_user

• Pattern 2: Resource Updates Channel — streams updates for a specific resource with authorization via reject

• Pattern 3: Chat Channel — bidirectional messaging with speak and typing actions, presence tracking

• Pattern 4: Dashboard Live Updates — broadcasts stats and activity feed to all account members

Each pattern follows the same structure:

• subscribed — find the resource, check authorization, call stream_for

• Class-level broadcast_* methods — render partials via ApplicationController.renderer

• A matching JavaScript subscription handler with a received(data) switch

Broadcasting

Broadcasting can be triggered from services, models, or callbacks. See broadcasting-and-stimulus.md for:

• From a service object — call EventsChannel.broadcast_update(event) after persistence

• From model callbacks — use after_create_commit to trigger channel broadcasts

• Turbo Streams integration — use broadcast_append_to / broadcast_remove_to helpers directly on models

• Stimulus controller — wrap the Action Cable subscription lifecycle inside a Stimulus controller for clean connect/disconnect management

• Performance patterns — connection limits, selective broadcasting, debounced broadcasts

Testing Channels

See testing.md for full specs. Key conventions:

Stub connection identity

stub_connection(current_user: user)

Assert subscription confirmed and streaming

subscribe(event_id: event.id) expect(subscription).to be_confirmed expect(subscription).to have_stream_for(event)

Assert rejection for unauthorized access

expect(subscription).to be_rejected

Assert broadcast payload

expect { described_class.notify(user, notification) }.to have_broadcasted_to(user).with(hash_including(type: "notification"))

Checklist

• Connection authentication configured

• Channel authorization implemented

• Client-side subscription set up

• Broadcasting from services/models

• Channel specs written

• Error handling in place

• Reconnection logic on client

• Performance limits configured

References

• channel-patterns.md — Full implementations of Notifications, Resource Updates, Chat, and Dashboard channels (Ruby + JavaScript)

• broadcasting-and-stimulus.md — Broadcasting from services/models, Turbo Streams integration, Stimulus controller, performance tips

• testing.md — RSpec channel specs, authorization specs, and system tests