Login user if possible

When using devise, one usually uses a before_action to authenticate a user:

before_action :authenticate_user!

This always requires a login though. What if you want to login a user if possible, but ignore it if the user is not logged in? You need to use warden (the underlying authentication framework devise uses) directly:

class MyController < ApplicationController
  skip_before_action :authenticate_user!
 
  def show
    user = warden.authenticate(scope: :user)
 
    if user
      # Logged in
    else
      # Not logged in
    end
  end
end