Django IntegrityError: (1048, "Column 'user_id' cannot be null")

Django IntegrityError: (1048, "Column 'user_id' cannot be null")

This is my models.py
class Cfituser(models.Model):
user = models.OneToOneField(User)
socialid = models.IntegerField(null=True)
accesstoken = models.CharField(max_length=255L, null = True)
class Meta:
db_table = 'CfitUser'
def __str__(self):
return "%s's profile" % self.user
@receiver(post_save, sender=User)
def create_cfituser(sender, instance, created, **kwargs):
if created:
Cfituser.objects.get_or_create(user=instance)
This is my views.py
@api_view(['GET', 'POST'])
def users_create(request, format = None):
"""
List all users, or create a new user.
"""
if request.method == 'GET':
cfituser = Cfituser.objects.all()
serializer = CfituserSerializer(cfituser, many=True)
return Response(serializer.data)
elif request.method == 'POST':
serializer = CfituserSerializer(data=request.DATA)
if serializer.is_valid():
print serializer.data
user = User.objects.create_user(username =
serializer.data['socialid'])
cfituser = Cfituser.objects.get(user = user)
cfituser.accesstoken = serializer.data['accesstoken']
cfituser.socialid = serializer.data['socialid']
cfituser.save()
serializer.save()
return Response(serializer.data, status=status.HTTP_201_CREATED)
else:
return Response(serializer.errors,
status=status.HTTP_400_BAD_REQUEST)
Whenever there is a HTTP Post request, my database tables are filled in as
expected but this error keeps popping up. I've tried almost every solution
available on SO but I'm stuck with this.
I have tried user = models.OneToOneField(User, null = True) but this leads
to two entries in my database table, one with user_id = NULL and one with
user_id = actualvalue.
Any suggestions on how to fix this?