models.py 文件源码

def save(self, *args, **kwargs):
        sid = transaction.savepoint()
        if self.pk is None:
            i = 1
            while self.pk is None:

                # Protection from infinite loop
                if i > 20:
                    raise IntegrityError('Too many iterations while generating unique Invoice number.')

                self.payment_no = random.randint(1, 2147483646)

                try:
                    super(Invoice, self).save(*args, **kwargs)
                except IntegrityError:
                    transaction.savepoint_rollback(sid)

                i += 1
        else:
            super(Invoice, self).save(*args, **kwargs)

        transaction.savepoint_commit(sid)
        transaction.commit()