Creating a extended user profile

I have an extended UserProfile model in django:

class UserProfile(models.Model):
  user = models.ForeignKey(User, unique=True)
  #other things in that profile

And a signals.py:

from registration.signals import user_registered
from models import UserProfile
from django.contrib.auth.models import User

def createUserProfile(sender, instance, **kwargs):
  profile = users.models.UserProfile()
  profile.setUser(sender)
  profile.save()

user_registered.connect(createUserProfile, sender=User)

I make sure the signal gets registered by having this in my __init__.py:

import signals

So that should create me a new UserProfile for every user that registers, right? But it doesn't. I always get "UserProfile matching query does not exist" errors when I try to log in, which means that the database entry isn't there.

I should say that I use django-registration, which provides the user_registered signal.

The structure of the important apps for this is, that I have one application called "users", there I have: models.py, signals.py, urls.py and views.py (and some other things which shouldn't matter here). The UserProfile class is defined in models.py.

Update: I changed the signals.py to:

from django.db.models.signals import post_save
from models import UserProfile
from django.contrib.auth.models import User

def create_profile(sender, **kw):
    user = kw["instance"]
    if kw["created"]:
        profile = UserProfile()
        profile.user = user
        profile.save()

post_save.connect(create_profile, sender=User)

But now I get a "IntegrityError":

"column user_id is not unique"

Edit 2:

I found it. Looks like somehow I registred the signal twice. The workaround for this is described here: http://code.djangoproject.com/wiki/Signals#Helppost_saveseemstobeemittedtwiceforeachsave

I had to add a dispatch_uid, now my signals.py looks like this and is working:

from django.db.models.signals import post_save
from django.contrib.auth.models import User
from models import UserProfile
from django.db import models

def create_profile(sender, **kw):
    user = kw["instance"]
    if kw["created"]:
        profile = UserProfile(user=user)
        profile.save()

post_save.connect(create_profile, sender=User, dispatch_uid="users-profilecreation-signal")