ActionCable

Message.rb

class Message < ApplicationRecord
  belongs_to :user
  belongs_to :channel

  validates :body, presence: true, length: {minimum: 2, maximum: 1000}

  after_create_commit {
    MessageBroadcastWorker.perform_async(self.id)
  }


  def timestamp
    created_at.strftime('%H:%M:%S %d %B %Y')
  end
end

MessageWorker.rb

class MessageBroadcastWorker
  include Sidekiq::Worker

  def perform(message_id)
    message = Message.where(id: message_id).first
    ActionCable.server.broadcast "room_#{message.channel_id}_channel:", message: render_message(message)
  end

  private

  def render_message(message)
    ApplicationController.renderer.render(partial: 'messages/message', locals: { message: message })
  end
end

room.js

jQuery(document).on 'turbolinks:load', ->
  messages = $('#messages')

  if messages.length > 0
    messages_to_bottom = -> messages.scrollTop(messages.prop('scrollHeight'))

    messages_to_bottom()

    App.room = App.cable.subscriptions.create {
        channel:"RoomChannel",
        channel_id: messages.data('channel-room-id')
      },
      connected: ->
        console.log('connected')
        console.log(App.room)
        # Called when the subscription is ready for use on the server

      disconnected: ->
        # Called when the subscription has been terminated by the server

      received: (data) ->
        console.log(data)
        messages.append data['message']
        messages_to_bottom()

      speak: (message, channel_id) ->
        @perform 'speak', message: message, channel_id: channel_id


    $('#new_message').submit (e) ->
      $this = $(this)
      textarea = $this.find('#message_body')
      if $.trim(textarea.val()).length > 1
        App.room.speak textarea.val(), messages.data('channel-room-id')
        textarea.val('')
      e.preventDefault()
      return false

RoomChannel.rb

# Be sure to restart your server when you modify this file. Action Cable runs in a loop that does not support auto reloading.
class RoomChannel < ApplicationCable::Channel
  def subscribed
    # stream_from "some_channel
    stream_from "room_#{params['channel_id']}_channel"
  end

  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end

  def speak(data)
    current_user.messages.create!(body: data['message'], channel_id: data['channel_id'])
  end
end