class User < ActiveRecord::Base
  belongs_to :account
  devise :database_authenticatable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable,
     :confirmable, :lockable, :timeoutable
  attr_accessible :email, :password, :password_confirmation, :remember_me
end

class Account < ActiveRecord::Base
  has_many :users, :dependent => :destroy
  attr_accessible :name, :account_type
end

class Account < ActiveRecord::Base
  has_many :users, :inverse_of => :account, :dependent => :destroy
  accepts_nested_attributes_for :users
  attr_accessible :name, :users_attributes
end

class User < ActiveRecord::Base
  belongs_to :account, :inverse_of => :users
  validates :account, :presence => true
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable,
         :confirmable, :lockable, :timeoutable
  attr_accessible :email, :password, :password_confirmation, :remember_me
end

it "should create account AND user through accepts_nested_attributes_for" do
  @AccountWithUser = { :name => "Test Account with User",
                       :users_attributes => [ { :email => "user@example.com",
                                                :password => "testpass",
                                                :password_confirmation => "testpass" } ] }
  au = Account.create!(@AccountWithUser)
  au.id.should_not be_nil
  au.users[0].id.should_not be_nil
  au.users[0].account.should == au
  au.users[0].account_id.should == au.id
end

resources :accounts, :only => [:index, :new, :create, :destroy]

class AccountsController < ApplicationController

  def new
    @account = Account.new
    @account.users.build # build a blank user or the child form won't display
  end

  def create
    @account = Account.new(params[:account])
    if @account.save
      flash[:success] = "Account created"
      redirect_to accounts_path
    else
      render 'new'
    end
  end

end

<h2>Create Account</h2>

<%= form_for(@account) do |f| %>
  <%= render 'shared/error_messages', :object => f.object %>
  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>

  <%= f.fields_for :users do |user_form| %>
    <div class="field"><%= user_form.label :email %><br />
    <%= user_form.email_field :email %></div>
    <div class="field"><%= user_form.label :password %><br />
    <%= user_form.password_field :password %></div>
    <div class="field"><%= user_form.label :password_confirmation %><br />
    <%= user_form.password_field :password_confirmation %></div>
  <% end %>

  <div class="actions">
    <%= f.submit "Create account" %>
  </div>
<% end %>

<%= f.fields_for :account do |account_form| %>
<div>
  <p>
    <%= account_form.label :name, "Account Name", :class => "label" %>
    <%= account_form.text_field :name, :class => "text_field" %>
    <span class="description">(e.g., enter your account name here)</span>
  </p>
</div>

<div>
  <p>
    <%= account_form.label :company, "Company Name", :class => "label" %>
    <%= account_form.text_field :company, :class => "text_field" %>
  </p>
</div>
<% end %>