Ok, I recommend something like this:

```python
old_course = m.Course.objects.with_id(course['id'])
if old_course:
    for key, value in course.iteritems():
        old_course[key] = value
    old_course.save()
    source['updated'] += 1
else:
    source['added'] += 1
```

Try that and let me know how well that works. Please test as follows:

1. Run `PYTHONPATH=.. python data/aggregator.py courses` _before making this fix_
1. Check that, indeed, no professor or ratings are shown.
1. Restore ratings and professors by running `PYTHONPATH=.. python data/aggregator.py all` w/o `update_courses()`
1. Make the suggested fix
1. Run `PYTHONPATH=.. python data/aggregator.py courses`, and ensure this time ratings/professors are preserved.

Does that make sense?