title: How to create a package of models in Django
body: <p>Having a quite large <code>models.py</code> file (which contains several models), I'm trying to refactor, with one model per file.</p>
  
  <p>I'm therefore trying to create a <code>models</code> package, with the following structure:</p>
  
  <ul>
  <li><code>app/models/__init__.py</code></li>
  <li><code>app/models/first_model.py</code></li>
  <li><code>app/models/second_model.py</code></li>
  </ul>
  
  <p>Unfortunately, I cannot get Django lazy reference mechanism to work well, i.e.:</p>
  
  <pre><code>first_model = models.ForeignKey('app.FirstModel')
  </code></pre>
  
  <p>returns the error that Django cannot find the model.</p>
  
  <p>Any idea? Thanks!</p>