action-cable-patterns

# 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: ```ruby # 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 ```ruby # 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](references/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: 1. `subscribed` — find the resource, check authorization, call `stream_for` 2. Class-level `broadcast_*` methods — render partials via `ApplicationController.renderer` 3. 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](references/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](references/testing.md) for full specs. Key conventions: ```ruby # 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](references/channel-patterns.md) — Full implementations of Notifications, Resource Updates, Chat, and Dashboard channels (Ruby + JavaScript) - [broadcasting-and-stimulus.md](references/broadcasting-and-stimulus.md) — Broadcasting from services/models, Turbo Streams integration, Stimulus controller, performance tips - [testing.md](references/testing.md) — RSpec channel specs, authorization specs, and system tests