title: AppEngine id/key/from_path is quite confusing what should I use
body: <p>I am back into AppEngine development.
  And I am quite hang up with the Datastorage.</p>
  
  <p>I am used to "ids", building the website with links like "/view?id=322345" gets me the GuestBook entry with this id voilà.</p>
  
  <p>But in AppEngine I always see the db.Key.from_path() method called and other stuff like "Ancestors" and "parents".</p>
  
  <p>In my project I have simple relationships like User->Phonenumbers, and I want to inspect each User via a GET url appending something id-like.
  Should I use the User models key() or how is this in AppEngine achieved?</p>
  
  <p>Currently if I want to add i.e. a PhoneNumber to the User I write the following:</p>
  
  <pre><code>class JoinHandler(webapp2.RequestHandler):
      def get(self):
          user_key = self.request.get('rlm')
          fon_number = PhoneNumber()
          fon_number.country = "deDE"
          fon_number.user = db.Key(user_key)
          fon_number.put()
          self.redirect("/")
  </code></pre>