将树重构为分层JSON对象

Question

我在玩MongoDB，我想将this tree重建为表示树的JSON对象：

{ 
    "_id" : "Books", 
    "children" : [ 
        { 
            "_id" : "Programming", 
            "children" : [ 
                {
                    "_id": "Languages"
                    "children": []
                },
                {
                    "_id" : "Databases", 
                    "children" : [ 
                        {
                            "_id": "MongoDB"
                            "children": []
                        },
                        {
                            "_id": "dbm"
                            "children": []
                        }
                    ] 
                }
            ] 
        }
    ] 
}

该树在数据库中表示为具有子引用的结构，与here完全相同。
正如我在教程中所读的那样，$ graphLookup聚合应该是一种方法，但是在执行这些聚合管道时：

[{$graphLookup: {
  from: 'categories',
  startWith: '$children',
  connectFromField: 'children',
  connectToField: '_id',
  as: 'children',
  maxDepth: 10
}}, {$match: {
  "_id": "Books"
}}]

我有一个根“书”，每个孩子都直接连接到根：

{ 
    "_id" : "Books", 
    "children" : [ 
        { 
            "_id" : "dbm", 
            "children" : [ ] 
        }, 
        { 
            "_id" : "Programming", 
            "children" : [ "Databases", "Languages" ] 
        }, 
        {
            "_id" : "Databases", 
            "children" : [ "MongoDB", "dbm" ] 
        }, 
        { 
            "_id" : "Languages",
            "children" : [ ] },
        { 
            "_id" : "MongoDB", 
            "children" : [ ] 
        } 
    ] 
}

编辑：我问是否有一种方法只能通过使用mongodb查询来解决此问题，而没有js递归函数。