在Django中可以默認基於float字段的整數字段嗎？

Question

展望基於另一個字段創建默認情況下，沿着線的東西：

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

然而，這將引發TypeError: unsupported operand type(s) for *: 'FloatField' and 'int'

FWIW，我想這無濟於事：

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) 

但是，被扔TypeError: 'int' object is not iterable

Answer 1

Opps，應該更仔細地閱讀堆棧跟蹤，結果發現E題是我的單元測試中的錯誤，而不是實際的代碼：

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) 

我不會刪除的情況下，這個問題的另一個Python和Django的小白做同樣的事情:)