actioncable_example.rb

# Uma pequena aplicação que utiliza o Action Cable para notificar novos comentarios dentro dela
# Criando a mensagem de evento (tirado de um turial do site: https://www.onehub.com/blog/2016/02/18/event-notifications-in-rails-5-with-actioncable/)

# rails g model event message:string

# rake db:migrate

# Criando controller e view para manipular os eventos
# rails g controller events index

#app/controllers/events_controller.rb
class EventsController < ApplicationController
  def index
    @events = Event.all.reverse
  end
end

#Partial que mostra a timestamp do evento e a mensagem de notificação:

#app/views/events/_event.html.erb
<div class="event">
  <%= event.created_at.to_formatted_s(:short) %>: <%= event.message %>
</div>

#app/views/index.html.erb
<h1>Activity</h1>
 
<div id="events">
  <%= render @events %>
</div>

#config/routes.rb
  
Rails.application.routes.draw do
  root to: 'events#index'
 
  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
 
  # Serve websocket cable requests in-process
  mount ActionCable.server => '/cable'
end




#app/assets/javascripts/channels/activity.coffee
#descomentar isso:
@App ||= {}
App.cable = ActionCable.createConsumer()

# rails g channel activity vai gerar os seguintes arquivos:
# app/channels/activity_channel.rb
# app/assets/javascripts/channels/activity.coffee


#app/channels/activity_channel.rb 
class ActivityChannel < ApplicationCable::Channel
  def subscribed
    stream_from "activity_channel"
  end
 
  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end
end

#app/assets/javascripts/channels/activity.coffee
App.activity = App.cable.subscriptions.create "ActivityChannel",
  connected: ->
    # Called when the subscription is ready for use on the server
 
  disconnected: ->
    # Called when the subscription has been terminated by the server
 
  received: (event) ->
    # Called when there's incoming data on the websocket for this channel
    $('#events').prepend "<div class='event'>#{event.message}</div>"

# Utilizando ActiveJob para manipular a transmissão das notificações
# rails g job EventBroadcast
# Vai gerar o arquivo: app/jobs/event_broadcast_job.rb

#app/jobs/event_broadcast_job.rb
class EventBroadcastJob < ApplicationJob
  queue_as :default
 
  def perform(event)
    ActionCable.server.broadcast 'activity_channel', message: render_event(event)
  end
 
  private
 
  def render_event(event)
    ApplicationController.renderer.render(partial: 'events/event', locals: { event: event })
  end
end

#app/models/event.rb
class Event < ApplicationRecord
  after_create_commit { EventBroadcastJob.perform_later self }
end

# Usando scaffolding para criar o model,a view e o controller dos comentários
# rails g scaffold comment comment:string
# rails db:migrate

#app/models/comment.rb
class Comment < ApplicationRecord
  after_create_commit { create_event }
 
  private
 
  def create_event
    Event.create message: "A new comment has been created"
  end
end