javascript - 获取mongoDB模型树结构中的所有父文档

Question

我正在为我的集合使用模型树结构。作为引用，我使用父字段。我需要从当前对象及其所有父对象获取属性。路径中的最后一个元素有一个字段“target”。所以我从

var result = parent = Articles.findOne({target: this.params._id});

do {
    parent = Articles.findOne({_id: parent.parent}).parent;
    for (var attrname in parent) { result[attrname] = parent[attrname]; }
}
while (parent.parent === null);

这对我来说似乎效率很低。是否可以用一行来获取包含所有元素的对象？然后我就可以处理该对象。

示例文档

{
    "_id" : "LD6h5ZcDuJjexfKfx",
    "title" : "title",
    "publisher" : "public",
    "author" : "author"
}
{
    "_id" : "KSiyh8zHRq8RZQ2E6",
    "edition" : "edition",
    "year" : "2020",
    "parent" : "LD6h5ZcDuJjexfKfx"
}
{
    "_id" : "5yCk4y25wrLBLZhyY",
    "pageNumbers" : "1-10",
    "target" : "9sjhzPhyTuQ5Kbh6v",
    "parent" : "KSiyh8zHRq8RZQ2E6"
}

因此，从 "target": "9sjhzPhyTuQ5Kbh6v" 开始，我想获取两个父文档(在本例中)。

至少我需要数据集

"title" : "title",
"publisher" : "public",
"author" : "author",
"edition" : "edition",
"year" : "2020",
"pageNumbers" : "1-10"

Answer 1

如果您想在单个查询中执行此操作，那么您需要遵循 array of ancestors Mongodb 中的模式。否则，您需要像您所做的那样递归遍历叶节点上方的分支。对于像您这样的深度较低的层次结构，这并不是一个很大的惩罚。

有了祖先数组，您的文档树将如下所示:

{
    "_id" : "LD6h5ZcDuJjexfKfx",
    "title" : "title",
    "publisher" : "public",
    "author" : "author",
}
{
    "_id" : "KSiyh8zHRq8RZQ2E6",
    "edition" : "edition",
    "year" : "2020",
    "ancestors" : ["LD6h5ZcDuJjexfKfx"],
    "parent" : "LD6h5ZcDuJjexfKfx"
}
{
    "_id" : "5yCk4y25wrLBLZhyY",
    "pageNumbers" : "1-10",
    "target" : "9sjhzPhyTuQ5Kbh6v",
    "ancestors" : ["LD6h5ZcDuJjexfKfx","KSiyh8zHRq8RZQ2E6"],
    "parent" : "KSiyh8zHRq8RZQ2E6"
}

获取文档及其父级:

Articles.find({ $or: [ { target: target },
  _id: { $in: Articles.findOne({ target: target }).ancestors }]});