title: django loop through queryset and add a new property
body: <p>I have two tables that I joined with a foreign key, I want to get all of the fields from one model and just one of the fields from the other model, how to I add on that field?</p>
  
  <pre><code>msos = Msos.objects.using('data').filter(id=121497).prefetch_related('mso_universe')
      for i in msos:
          for x in i.mso_universe.all():
              # I want to add x.population to each i
      data = serialize('json', data)
      return HttpResponse(data)
  </code></pre>