问Django中的查询树模型

EN

from django.db import models


class Comment (models.Model):
    # if parent is blank, comment is top level
    parent = models.ForeignKey('Comment',
                           related_name='children',
                           null=True)
    text = models.TextField(blank=True)

    def __repr__(self):
        return self.text


"""
from tree.models import Comment
c1 = Comment(text='c1')
c1.save()
c11 = Comment(text='c11', parent=c1)
c12 = Comment(text='c12', parent=c1)
c11.save()
c12.save()
c111 = Comment(text='c111', parent=c11)
c112 = Comment(text='c112', parent=c11)
c111.save()
c112.save()
c1.children.all() -> return [c111, c112] should return [c111, c112, c11, c12]
"""

            c1
     c11          c12
c111   c112