#The simple example of Facebook chat bot using Ruby on Rails

Now I will share you how to create a basic Facebook chat bot using RoR. Following steps:

###Step 1

• Go to the manager page of your facebook web app and chose Messenger:

https://developers.facebook.com/apps/your-app-id/messenger/

• Chose a page which you want to test with this chat bot, and remember the token which using for the next step:

• Chose the webhook events and add the chosed page to the subscribtion:

###Step 2

• Create a new Rails app

rails new facebook-bot-chat-rails

• Create the Messengers controller with two actions: index, create

rails generate controller Messengers index create

#app/controllers/messengers_controller.rb
class MessengersController < ApplicationController
  skip_before_action :verify_authenticity_token, only: [:create]
  def index
    render :json => params["hub.challenge"]
  end
end

#config/routes.rb
resources :messengers, only: [:index, :create]

###Step 3

You can use the ngrok to test the app from local.

• Go to the Webhooks tab on the menu of Facebook app manager page

• Add the callback url https://8d206053.ngrok.io/messengers with the token which you saved at step 2:

###Step 4

• Back to the Rails app, and add the action create to recieve the message from Facebook webhook.

class MessengersController < ApplicationController
  ...
  def create
    messaging_events = params[:entry][0][:messaging]
    messaging_events.each_with_index do |messaging_event, index|
      event = params[:entry][0][:messaging][index]
      sender = event[:sender][:id]
      if event[:message] && event[:message][:text]
        text = event[:message][:text]
        send_text_message sender, text
      end
    end
    render :json => "ok"
  end

  private
  def send_text_message sender, text
    puts sender
    messageData = { text: text }
    token = "your-token"
    uri = URI.parse("https://graph.facebook.com/v2.6/me/messages?access_token=" + token)
    http = Net::HTTP.new(uri.host, uri.port)
    http.use_ssl = true
    param = { recipient: { id: sender }, message: messageData }

    header = {"Content-Type" =>"application/json"}
    resp = http.post(uri.request_uri, param.to_json, header)
    resp
  end
end

Ok, now your app is ready! Good luck.