[Fixed]-Calculate DateField until days in Django

Add a custom save method to your model class. Sample code below will automatically compute expiry date only upon creation. Subsequent modification of the record will not trigger this automatic computation.

class ModelName(models.Model):
    created = models.DateTimeField()
    expired = models.DateTimeField(blank=True, null=True)

    def save(self, *args, **kwargs):
        if not self.pk:
            self.expired = self.created + datetime.timedelta(days=30)
        super(ModelName, self).save(*args, **kwargs)