Question

I am creating a one-to-one relationship to user called user_info.
Below is the working solution.

In user.rb

has_one :user_info
accepts_nested_attributes_for :user_info, :allow_destroy => true
attr_accessible :username, :email, :password, :password_confirmation, :remember_me, :user_info_attributes

In user_info.rb

belongs_to :user
attr_accessible :first_name, :last_name

In devise/registrations/edit.html.erb

<% resource.build_user_info if resource.user_info.nil? %>
<%= form_for(resource, :as => resource_name, :url => registration_path(resource_name), :html => { :method => :put }) do |f| %>
    ...
    <%= f.fields_for :user_info do |info| %>
        <%= info.text_field :first_name %>

I understand that I should not include the build in the view. But I do not want to ‘touch’ the devise controller or model. This is the easiest way.

Answer 1

Turns out that the build line is not working properly in the view.

Should be:
<% resource.build_user_info if resource.user_info.nil? %>