Devise + MongoDB embedded users

account.rb

class Account
  include Regexs
    
  include Mongoid::Document
  include Mongoid::Timestamps

  #has_many :users
  embeds_many :users, store_as: :credentials

  scope :for, ->(current_user_id){ where('credentials._id' => current_user_id) }
  scope :via_oauth, ->(auth){ where('credentials.provider' => auth.provider, 'credentials.uid' => auth.uid) }

  def find_user(user_id)
    users.find(user_id) unless user_id.nil?
  end
end

application_controller.rb

class ApplicationController < ActionController::Base
  def current_user_id
    session["warden.user.user.key"].first.first if session["warden.user.user.key"].present?
  end

  def current_user
    return @current_user unless @current_user.nil?
    account = @current_account || Account.for(current_user_id).first
    @current_user ||= account.find_user(current_user_id) if account.present?
  end

  def current_account
    @current_account ||= @current_user.account if @current_user.present?
  end
end