I have this Django model:
from django.contrib.gis.db import models
class Event(models.Model):
address = models.TextField()
point = models.PointField
I don't think you have many options here. Either you use a placeholder such as (0, 0), or you encapsulate the point in an object and reference the object everywhere you need the point. That way the reference to the object could be made nullable, but the extra join would hurt performance and complicate things.