title: Rails nested resources, how do I create two new resources when I need the other's id in the GET request?
body: <p>Pretty much as the title suggest. I have two models, routes like this:</p>
  
  <pre><code>resources :users do
    resources :books
  end
  </code></pre>
  
  <p>- which gives me exactly the kind of urls I'm looking for. The problem is that I need to have a logic where a <em>not</em> logged in user can go in and click "create book", and in the new-page chose to click "new user" or "I have an account", which via javascript loads a form for a new user with all its params, or loads a form with only email and password. How do I create this route to work? With these routes it seems I get the path <code>/users/:user_id/books/new</code>, but then I need the user's ID, which I don't have.</p>
  
  <p>Any Ideas?</p>
  
  <p>By the way. User has_many :books, Book belongs_to :user.</p>