Authentication using Rails' scaffold

In essence, the authentication scaffold that Rails 8 comes with is custom authentication so we need to do a few things to ensure it's working properly with Avo.

1. Set the current user

The scaffold uses the Current.user thread-safe global to hold the current authenticated user so we need to tell Avo how to fetch them.

# config/initializers/avo.rb
Avo.configure do |config|
  # other pieces of configuration

  # tell Avo how to find the current authenticated user.
  config.current_user_method do
    Current.user
  end
end

2. Set the sign out link

The scaffold uses the SessionsController to sign out the user so the link should be sessions_path. We need to add that to Avo as well.

# config/initializers/avo.rb
Avo.configure do |config|
  # other pieces of configuration

  # tell Avo how to sign out the authenticated user.
  config.sign_out_path_name = :session_path
end

3. Ensure only authenticated users are allowed on Avo

Now, here comes the part which might seem unfamiliar but it's actually pretty standard.

The scaffold adds the Authentication concern to your ApplicationController which is great. We will add it to Avo's ApplicationController and also add the before_action, but instead of just appending it wil will prepend it so we can ensure it will be fired as soon as possible in the request lifecycle.

Since require_authentication runs in the Avo context, it's necessary to delegate the new_session_path to the main_app to ensure proper routing.

# app/controllers/avo/application_controller.rb
module Avo
  class ApplicationController < BaseApplicationController
    include Authentication
    delegate :new_session_path, to: :main_app

    # we are prepending the action to ensure it will be fired very early on in the request lifecycle
    prepend_before_action :require_authentication
  end
end

INFO

If you don't have the app/controllers/avo/application_controller.rb file present in your app, you can eject it using this command:

rails generate avo:eject --controller application_controller