[Answered ]-How do I save to Django's database manually?

Since the save method returns an Model object, you can modify it again before definitively save it to the database :

if form.is_valid():
    prefs = form.save(commit=False)
    prefs.user = request.user
    # if they logged in through social network there are other fields
    if socialacc:
        prefs.firstname = socialacc[0].extra_data['firstName']
        ...
    prefs.save()