cqtu/contest/signals.py

def checkForShadowCall(sender, instance, created, raw, **kwargs):
    """ Check for existing shadow call. If present copy it's data and delete it. """
    if created:
        # to prevent circular imports we import ShadowCall here
        from .models import ShadowCall

        try:
            shadow = ShadowCall.objects.get(username=instance.username)
            instance.ref = shadow.ref
            instance.location = shadow.location
            instance.opName = shadow.opName
            instance.regTime = shadow.regTime

            instance.save()
            shadow.delete()
        except ShadowCall.DoesNotExist:
            pass