Infinite classification

#  List of commodity types 
class Cate(models.Model):
    name = models.CharField(' Category name ', max_length=30)
    #  Link yourself  
    cid = models.ForeignKey('self', on_delete=models.CASCADE, related_name='subs', null=True, blank=True)

    def __str__(self):
        return self.name

    class Meta:
        db_table = 'cate'


#  Sort and group 
class Group(models.Model):
    name = models.CharField(' Channel group name ', max_length=30)
    # 1:1 Model class 
    cate = models.OneToOneField(Cate, on_delete=models.CASCADE, related_name=' Primary categories ')
    group_url = models.CharField(' Channel group address ', max_length=200, default=' http://jd.com')
    sequence = models.IntegerField(' Display order ', default=0)

    def __str__(self):
        return self.name

    class Meta:
        db_table = 'group'