我创建了一个通过模型,所以我可以向m2m字段添加一个订单字段,但我遇到问题,通过def number自动递增订单字段()。当我添加一个对象时,我得到TypeError不受支持的操作数类型(+):'dict'和'int',我不知道为什么。有任何想法吗?Django TypeError不支持的操作数类型为+:'dict'和'int'
models.py:
class Playlist(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)
name = models.CharField(max_length=50)
tracks = models.ManyToManyField(Track, through='PlaylistTrack')
def __str__(self):
return self.name
class PlaylistTrack(models.Model):
def number():
last_order = PlaylistTrack.objects.all().aggregate(Max('order'))
if last_order == None:
return 1
else:
return last_order + 1
track = models.ForeignKey(Track)
playlist = models.ForeignKey(Playlist)
order = models.PositiveIntegerField(default=number)
class Meta:
ordering = ['order']