Question

在这个模型中：

class Rank(models.Model):
    User = models.ForeignKey(User)
    Rank = models.ForeignKey(RankStructure)
    date_promoted = models.DateField()

    def __str__(self):
        return self.Rank.Name.order_by('promotion__date_promoted').latest()

我收到错误：

Exception Value:    

'str' object has no attribute 'order_by'

我希望最新的Rank为默认值。我该如何设置？

感谢。

更新＃1

添加了排名结构

class RankStructure(models.Model):
    RankID = models.CharField(max_length=4)
    SName = models.CharField(max_length=5)
    Name = models.CharField(max_length=125)
    LongName = models.CharField(max_length=512)
    GENRE_CHOICES = (
        ('TOS', 'The Original Series'),
        ('TMP', 'The Motion Picture'),
        ('TNG', 'The Next Generation'),
        ('DS9', 'Deep Space Nine'),
        ('VOY', 'VOYAGER'),
        ('FUT', 'FUTURE'),
        ('KTM', 'KELVIN TIMELINE')
    )
    Genre = models.CharField(max_length=3, choices=GENRE_CHOICES)
    SPECIALTY_OPTIONS = (
        ('CMD', 'Command'),
        ('OPS', 'Operations'),
        ('SCI', 'Science'),
        ('MED', 'Medical'),
        ('ENG', 'Engineering'),
        ('MAR', 'Marine'),
        ('FLT', 'Flight Officer'),
    )
    Specialty = models.CharField(max_length=25, choices=SPECIALTY_OPTIONS)
    image = models.FileField(upload_to=image_upload_handler, blank=True)

这是Class Rank中Rank引用的Rank_structure。用户外键进入标准用户表。

Answer 1

您收到错误的原因是self.Rank.Name不是ModelManager，您可以在其上调用order_by。如果您想拨打objects，那么您需要在某处order_by。我们无法帮助您使用所需查询的django格式，除非您还按照多个评论者的要求发布模型定义。也就是说，我怀疑你想要的是：

def __str__(self):
    return self.objects.filter(Rank_id=self.Rank_id).order_by('date_promoted').latest().User.Name

如何获得最新的django模型

1 个答案: