title: Saving ForeignKey objects in Django
body: <p>I'm completely stumped as to why this isn't working:</p>
  
  <pre><code>flight = Flight.objects.get(pk=flight_id)
  print "old", flight.route.pk ## `route` is a ForeignKey field to model Route
  print "new", new_route.pk
  flight.route=new_route  # new_route is a newly created Route object
  flight.save()
  print "db", Flight.objects.get(pk=flight_id).route.pk
  </code></pre>
  
  <p>this is the output:</p>
  
  <pre><code>old 4800
  new 7617
  db 4800
  </code></pre>
  
  <p>Is there some special way I need to call save() on the flight to get it to actually save?</p>
  
  <p>edit: my models look like this:</p>
  
  <pre><code>class Flight(models.Model):
      route = models.ForeignKey(Route, blank=True, null=True, related_name="flight")
  
  class Route(models.model):
      # a bunch of CharFields and IntegerFields
  </code></pre>