title: django get model with foreign key
body: <p>Let's say I have 2 tables in my DB. One of them is called Person which has attributes 'name' and 'id' and the other one is called Role which has attributes 'person'(which is a foreign key to the id in Person table) and 'id'.
  Now I'd like to make a query that given a name like David, finds all the persons with that name and also returns the Roles associated with them. We know that every Person is associated to at most 1 role.</p>
  
  <p>I know that I cannot use <code>Person.objects.filter(name=David).select_related('Role')</code> Because Role is not Person's attribute. Is there anyway I can get this with only 1 hit to DB?</p>