def pre_save(self, model_instance, add):
        """Generate ID if required."""
        value = super(AleaIdField, self).pre_save(model_instance, add)
        if (not value) and self.default in (meteor_random_id, NOT_PROVIDED):
            value = self.get_seeded_value(model_instance)
            setattr(model_instance, self.attname, value)
        return value
Generate ID if required.