Event based system in Ruby (on Rails) - Part 2

ruby
events

23 Sep 2023

In my previous post about an “event based system in Ruby (on Rails) - Part 1” I stated that I like the way of using the MessageBus gem more than the ergonomics of the Wisper gem. In the this blog post I’d like to show how one would achieve the same thing with Wisper and I might have changed my opinion on this.

The User model will be adjusted to this:

# app/models/user.rb
class User < ApplicationRecord
  include Wisper::Publisher

  after_commit on: :create do
    broadcast(:models_user_created, id)
  end
end

The initializer will look like this:

# e.g. config/initializer/wisper.rb
Rails.application.reloader.to_prepare do
  Wisper.subscribe(
    Class.new do
      def models_user_created(user_id)
        NewUserNotificationJob.perform_later({ "id" => user_id })
      end
    end.new,
    scope: User, on: :models_user_created,
  )
end

As you can see, the changes are nearly the same. And if you consider that the MessageBus gem can do much more than this, it might be overkill to what I wanted to achieve.

A cleaner initializer

You could also achieve a cleaner initializer if you add a listener method to the NewUserNotificationJob and just add this listener in the initializer:

# e.g. config/initializer/wisper.rb
Rails.application.reloader.to_prepare do
  Wisper.subscribe(NewUserNotificationJobV2, scope: User, on: :models_user_created)
end

# app/jobs/new_user_notification_job.rb
class NewUserNotificationJob < ApplicationJob
  def self.models_user_created(user_id)
    NewUserNotificationJobV2.perform_later({ "id" => user_id })
  end

  # Rest of the job implementation ...
end

NOTE: This PR contains a very basic implementation of what the blog post described.