Rails Devise error on building one to one relationship upon registration - ruby-on-rails

Question

I want to create a one to one relationship, User -> Account upon Devise registration. I thought I had it figured out with the following code.
# account.rb
class Account < ActiveRecord::Base
belongs_to :user
end
# user.rb
class User < ActiveRecord::Base
has_one :account
end
# registrations_controller.rb
def create
super
current_user.build_account(account_params).save
end
And this code works about 80% of the time so far. But every once and a while, I get the following error.
undefined method 'build_account' for nil:NilClass
app/controllers/users/registrations_controller.rb:13:in 'create'
Clearly, the error is telling me, you cannot build_account when current_user is nil. That makes sense to me, but
Why does that happen only some of the time?
What is a more consistent way to build this one to one relationship upon Devise user registration?

Answer 1

When I do this I like to use nested forms.
# user.rb
class User < ActiveRecord::Base
belongs_to :account
accepts_nested_attributes_for :account
end
# account.rb
class Account < ActiveRecord::Base
belongs_to :user
end
#views registrations/new.html.haml
= simple_form_for(resource, :as => resource_name, :url => registration_path(resource_name)) do |f|
%ul
- resource.errors.full_messages.each do |e|
%li=e
= f.simple_fields_for :account do |account_form|
...
...
#Controller
class Users::RegistrationsController < Devise::RegistrationsController
def new
resource = build_resource({})
resource.build_account
respond_with resource
end
def create
build_resource(sign_up_params)
if resource.save
...
else
...
end
end
private
def sign_up_params
allow = [:first_name, :last_name, :phone, :email, :password, :password_confirmation, :agree_newsleter, account_attributes: [:name, :phone, :website]]
params.require(resource_name).permit(allow)
end
end