Question

希望根据另一个字段创建默认值，类似于：

class Track(models.Model):
    distance = models.FloatField()
    timeout = models.PositiveSmallIntegerField(default=int(distance * 2))

然而，这会引发TypeError: unsupported operand type(s) for *: 'FloatField' and 'int'

FWIW，我试过这个无济于事：

class Track(models.Model):
    distance = models.FloatField()
    timeout = models.PositiveSmallIntegerField()

    def save(self, *args, **kwargs):
        if (self.timeout is None):
            self.timeout = int(self.distance * 2)
            super(Track, self).save(*args, **kwargs)

但那是投掷TypeError: 'int' object is not iterable

Answer 1

Opps，应该更仔细地阅读堆栈跟踪，结果问题是我的单元测试中的错误而不是实际的代码：

def test_timeout_defaults_to_twice_distance_when_none(self):
    Track.objects.create(name='Test Track', distance=10)
    track = Track.objects.get(1) # Should've been get(id=1)
    self.assertEqual(20, track.timeout)

如果另一个Python和Django noob做同样的事情，我不会删除这个问题：）

在Django中是否可以基于浮点字段默认整数字段？

1 个答案: