application_controller.rb

require 'castle/support/rails'

class ApplicationController < ActionController::Base
  
  before_action do
    next unless request.path == '/users/sign_in'

    email = request.params['user']['email']
    password = request.params['user']['password']

    user = User.find_by_email(email)

    if user.present? && user.valid_password?(password)
      begin
        verdict = castle.track(
          event: '$login.succeeded',
          user_id: user.id,
          traits: {
            email: user.email,
            created_at: user.created_at
          }
        )
      rescue ::Castle::Error => e
      end
    else
      begin
        castle.track(
          event: '$login.failed',
          user_id: user && user.id,
          traits: {
            email: email
          }
        )
      rescue ::Castle::Error => e
      end
    end
  end

  # ...
end