Why doesn't select_related() work in Django 1.6?

Question

Django

There are models in which there are fields:

from django.contrib.auth.models import User

class Profile(models.Model):
    user = models.OneToOneField(User, primary_key=True, unique=True, related_name='user_id')
    ...

class Comments(MPTTModel):
    ...
    user = models.ForeignKey(Profile, related_name='id_user_com')
    ...

When trying to request a username from the Comment model, an error is displayed that there is no such attribute:

c = Comments.objects.select_related('id_user_com__user_id').get(id=4)
print c.username

AttributeError: 'Comment' objects has no attribute 'username'

Tell me, please, I'm doing it wrong.
Ultimately, I need to serialize this request:

serializers.serialize('json', c, fields=('id','text','level','rating','username'))

Perhaps there is another way to get the username instead of its id.
Thanks in advance for your replies.

Answer 1

Access remains the same: c.user.username
select_related doesn't add fields to models, it just does the necessary joins