Messenger bot using Rails: setup for multiple pages

Question

I want to create a Messenger Bot used by different users for their Facebook pages. I created a rails app and use the facebook-messenger gem.

I successfully created the bot and it works when I do the set up for one page. Now, I follow the instructions to make my bot live on multiple Facebook Pages (see "Make a configuration provider" section).

I'm new to rails and I'm not sure where to put the class ExampleProvider? I put it in my config/application.rb file:

require_relative 'boot'

require 'rails/all'

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module BotletterApp
  class Application < Rails::Application
    # Settings in config/environments/* take precedence over those specified here.
    # Application configuration should go into files in config/initializers
    # -- all .rb files in that directory are automatically loaded.
    config.paths.add File.join('app', 'bot'), glob: File.join('**', '*.rb')
    config.autoload_paths += Dir[Rails.root.join('app', 'bot', '*')]
  end

  class BotProvider < Facebook::Messenger::Configuration::Providers::Base
    def valid_verify_token?(verify_token)
      bot.exists?(verify_token: verify_token)
    end

    def app_secret_for()
      ENV['APP_SECRET']
    end

    def access_token_for(page_id)
      bot.find_by(user_id: page_id).page_access_token
    end

    private

    def bot
      MyApp::Bot
    end
  end

  Facebook::Messenger.configure do |config|
    config.provider = BotProvider.new
  end
end

Then I have my app/bot/setup.rb file to create the bot. I don't know how to use the provider I created in place of the ENV variables?

require "facebook/messenger"

include Facebook::Messenger

Facebook::Messenger::Subscriptions.subscribe(access_token: ENV["ACCESS_TOKEN"])

Facebook::Messenger::Profile.set({
  get_started: {
    payload: 'GET_STARTED_PAYLOAD'
  }
}, access_token: ENV['ACCESS_TOKEN'])

I searched in the Rails documentation how to make it work but unfortunately could not find anything.

UPDATE:

Now I'm able to set up the bots for different pages. Unfortunately, the following line of my ConfigProvider is getting an error:

config/initializers/config_provider.rb

def bot
    Rails.application.class.parent::Bot
  end
I'm getting the following error:

NameError (uninitialized constant BotletterApp::Bot):

config/initializers/config_provider.rb:17:in bot' config/initializers/config_provider.rb:7:inapp_secret_for'

Do you know how should I name my app?

My BotModule:

module BotletterApp
  class Application < Rails::Application
    # Settings in config/environments/* take precedence over those specified here.
    # Application configuration should go into files in config/initializers
    # -- all .rb files in that directory are automatically loaded.
    config.paths.add File.join('app', 'listen'), glob: File.join('**', '*.rb')
    config.autoload_paths += Dir[Rails.root.join('app', 'listen', '*')]
  end
end

UPDATE, it works with ::Application, here is the new file:

class ConfigProvider < Facebook::Messenger::Configuration::Providers::Base
  def valid_verify_token?(verify_token)
    ENV['VERIFY_TOKEN']
  end

  def app_secret_for(page_id)
    ENV['APP_SECRET']
  end

  def access_token_for(page_id)
    CoreBot.find_by_page_id(page_id).page_access_token
  end

  private

  def bot
    BotletterApp::Application
  end
end

Facebook::Messenger.configure do |config|
  config.provider = ConfigProvider.new
end

The problem is I get the following error unless my db query seems working (it works in the rails console):

ActiveRecord::StatementInvalid (SQLite3::SQLException: no such column: page_id.id: SELECT "core_bots".* FROM "core_bots" WHERE "page_id"."id" = ? LIMIT ?):

Answer 1

Moving to an answer for improved readability ;)

Regarding 'plain'... Instead of

def bot
  BotletterApp::Application
end

use

def bot
  Bot
end

or (it looks like you named your model containing all pages CoreBot(?) (assuming you have a typical ActiveRecord model in /app/models/core_bot.rb, I was assuming Bot)

def bot
  CoreBot
end

Then you should be able to use the template code from the README.md

As for your latest problem: it seems like the access_token_for-method gets called with a hash, searching with something like {id: 1}. You might want to check where that value is coming from. I would suggest to take a few steps back, and stay closer to the template code.