Pymongo节点后代具有特定的顺序

Question

考虑到我在MongoDB中有一棵树，如图所示。

我想做的是按特定顺序获取节点后代。

def descendants(nodeID):
    descendants = []
    stack = []

    item = vt.comments.find_one({'_id': nodeID })
    stack.append(item)
    stack.sort(key=lambda x: x['order'])

    while(len(stack) > 0):
        currentNode = stack.pop()
        children = vt.comments.find({'parent': currentNode["_id"] })

        for child in children:
            descendants.append(child['_id'])
            stack.append(child)
            stack.sort(key=lambda x: x['order'])

    print(descendants)

我的程序与此类似，当我调用此函数时  像这样descendants(0)它的输出类似于：

  

[1,2,3,12,13,14,15,8,9,10,11,4,5,6,7,16,17,18,19]

但我想做的是按此顺序访问项目：

  

[1,4,5,6,7,2,8,9,10,11,3,12,16,17,18,19,13,14,15]

Answer 1

这是例外情况：

def descendants(nodeID):

    descendants = []
    stack = []

    item = vt.comments.find_one({'_id': nodeID })
    stack.append(item)
    stack.sort(key=lambda x: x['order'], reverse=True)

    while(len(stack) > 0):
        currentNode = stack.pop()
        descendants.append(child['_id'])
        children = vt.comments.find({'parent': currentNode["_id"] })

        for child in children:
            stack.append(child)
            stack.sort(key=lambda x: x['order'], reverse=True)

    print(descendants)