先搁置了

comment/models.py新建回复树结构所需字段。其为回复树的根。并更新数据库和admin.py

class Comment(models.Model):
    ......
     user = models.ForeignKey(User, related_name='comments',on_delete=models.DO_NOTHING) # 谁评论
    #   related_name 解决外键冲突
    # parent_id = models.IntegerField(default=0)
    root = models.ForeignKey('self',related_name='root_comment',null=True,on_delete=models.DO_NOTHING)
    parent = models.ForeignKey('self', null=True,related_name='parent_comment', on_delete=models.DO_NOTHING)
    reply_to = models.ForeignKey(User,null=True, related_name='replies',on_delete=models.DO_NOTHING)   # 评论谁
    def __str__(self):
        return self.text
    # 在后台显式显示父节点的评论内容方便后台管理