@staticmethod

    def get_instance(user):

        ''' Returns the instance of attendee for the given user, or creates

        a new one. '''

        try:

            return Attendee.objects.get(user=user)

        except ObjectDoesNotExist:

            return Attendee.objects.create(user=user)

    def save(self, *a, **k):

        while not self.access_code:

            access_code = util.generate_access_code()

            if Attendee.objects.filter(access_code=access_code).count() == 0:

                self.access_code = access_code

        return super(Attendee, self).save(*a, **k)

    user = models.OneToOneField(User, on_delete=models.CASCADE)

    # Badge/profile is linked

    access_code = models.CharField(

        max_length=6,

        unique=True,

        db_index=True,

    )

    completed_registration = models.BooleanField(default=False)

class AttendeeProfileBase(models.Model):

    ''' Information for an attendee's badge and related preferences.

    Subclass this in your Django site to ask for attendee information in your

    registration progess.

     '''

    objects = InheritanceManager()

    @classmethod

    def name_field(cls):

        ''' This is used to pre-fill the attendee's name from the

        speaker profile. If it's None, that functionality is disabled. '''

        return None

    def invoice_recipient(self):

        ''' Returns a representation of this attendee profile for the purpose

        of rendering to an invoice. Override in subclasses. '''

        # Manual dispatch to subclass. Fleh.

        slf = AttendeeProfileBase.objects.get_subclass(id=self.id)

        # Actually compare the functions.

        if type(slf).invoice_recipient != type(self).invoice_recipient: