title: Prepend sign_up page with a condition?
body: <p>I want to ask user a question, and let him sign up <em>only</em> if the user answers my question correctly. I searched <a href="https://github.com/plataformatec/devise/wiki/How-Tos">devise how-to acticles</a> but my case doesn't seem to be there.</p>
  
  <p>Is there an idiomatic way to deal with this situation?</p>
  
  <p>The first thought might be to use javascript, but answers are stored in LDAP, and I expect it will be easier to deal with this in rails.</p>
  
  <p>I was also thinking about disabling <code>/users/sign_up</code> route, invoke the action (<code>devise/registration#new</code>) manually and render the view (<code>devise/registration/new</code>).</p>
  
  <p>Another way I can think of, is to run a background daemon, which will collect session id, where user answered the questions correctly. On correct answer user will be redirected to the publicly available sign up page, which will get check user's session id with the daemon.</p>