按另一个 MongoDB 结果排序 MongoDB 结果返回 [null, null, null]

Question

我正在执行两个 MongoDB 查询，然后我想同步结果数组，以确保它们的顺序相同。

第一个数组是一组 (20) 个问题 ID（这是正确的顺序）：

q_id_arr: [
   "5f86da2d37e3d200040ba523",
   "5f86b6ce37e3d200040ba4c6",
   "5ffc4abea04f3c0004e46cf3",
   "5f86b66537e3d200040ba4c5",
   "5f87f368554f370004ed17b4",
   "5f86e48c37e3d200040ba53c",
   "5ffc4dc4a04f3c0004e46d0b",
   "5f86e19037e3d200040ba534",
   "5f86aaa237e3d200040ba49b",
   "5ffc479ba04f3c0004e46ce0",
   "5f86b9dc37e3d200040ba4d2",
   "5f85828e0e1bd30004361430",
   "5f8700c937e3d200040ba548",
   "5f86d81737e3d200040ba51c",
   "5f8708d237e3d200040ba568",
   "5f87060d37e3d200040ba55c",
   "5f857dac0e1bd3000436141c",
   "5f85703e0e1bd300043613ec",
   "5f87e9d4554f370004ed178e",
   "5f8073c04ad88e00041f015f"
]

第二个数组是一组 (20) 个与问题 ID 相关的结果：

team_trends: [
   {
      "_id":"5f87e9d4554f370004ed178e",
      "positive":0.93,
      "engaged":0.558
   },
   {
      "_id":"5f86e19037e3d200040ba534",
      "positive":0.585,
      "engaged":0.567
   },
   {
      "_id":"5f85828e0e1bd30004361430",
      "positive":0.7,
      "engaged":0.666
   },
   {
      "_id":"5f8073c04ad88e00041f015f",
      "positive":0.31,
      "engaged":0.30999999999999994
   },
   {
      "_id":"5f87f368554f370004ed17b4",
      "positive":0.5449999999999999,
      "engaged":0.57
   },
   {
      "_id":"5f86b6ce37e3d200040ba4c6",
      "positive":0.855,
      "engaged":0.46599999999999997
   },
   {
      "_id":"5f857dac0e1bd3000436141c",
      "positive":0.92,
      "engaged":0.524
   },
   {
      "_id":"5f85703e0e1bd300043613ec",
      "positive":0.15,
      "engaged":0.39
   },
   {
      "_id":"5f86aaa237e3d200040ba49b",
      "positive":0.15000000000000002,
      "engaged":0.584
   },
   {
      "_id":"5f86b66537e3d200040ba4c5",
      "positive":0.37,
      "engaged":0.386
   },
   {
      "_id":"5f86e48c37e3d200040ba53c",
      "positive":0.615,
      "engaged":0.548
   },
   {
      "_id":"5ffc479ba04f3c0004e46ce0",
      "positive":0.42000000000000004,
      "engaged":0.583
   },
   {
      "_id":"5f86b9dc37e3d200040ba4d2",
      "positive":0.68,
      "engaged":0.662
   },
   {
      "_id":"5f86d81737e3d200040ba51c",
      "positive":0.03,
      "engaged":0.516
   },
   {
      "_id":"5f87060d37e3d200040ba55c",
      "positive":0.14,
      "engaged":0.454
   },
   {
      "_id":"5f86da2d37e3d200040ba523",
      "positive":0.47,
      "engaged":0.41500000000000004
   },
   {
      "_id":"5f8708d237e3d200040ba568",
      "positive":0.17,
      "engaged":0.76
   },
   {
      "_id":"5ffc4dc4a04f3c0004e46d0b",
      "positive":0.395,
      "engaged":0.53
   },
   {
      "_id":"5ffc4abea04f3c0004e46cf3",
      "positive":0.365,
      "engaged":0.679
   },
   {
      "_id":"5f8700c937e3d200040ba548",
      "positive":0.93,
      "engaged":0.6980000000000001
   }
]

我想将team_trends重组为与q_id_arr相同的顺序

这是我正在使用的代码（遵循this SO Answer）：

let c = [];
q_id_arr.forEach((q_oid => c.push(team_trends.find((obj => obj._id == q_oid)))));

但是，当我打印 console.log("the result of c"+ c) 时，我得到了这个结果：

the result of c: [null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null]

这是正确的方法吗？任何建议表示赞赏！

更多详情：

在这一步之前，我通过映射aggregate 结果获得了q_id_arr，如下所示：

let q_id_arr = await user_trends.map(({ question_oid }) => question_oid)

当我测试console.log(typeof q_id_arr) 时，它返回了object。

如何对对象进行排序？？

Answer 1

解决问题的最终代码。

user_trends.forEach((user => c.push(team_trends.find((obj => obj._id.toString() === user.question_oid.toString())))));

这里有几点需要注意：

1. 如果您使用的是 mongoose，那么它已经从聚合函数返回了一个数组。
2. Mongoose 在其核心使用 MongoDB NodeJs 本机驱动程序。在核心驱动 ObjectId 中有一个函数.equals(otherId)。最好使用此函数进行 id 比较。

参考资料：

1. Comparing mongoose _id and strings
2. .aggregate(...).toArray is not a function
3. https://mongodb.github.io/node-mongodb-native/api-bson-generated/objectid.html#equals

Answer 2

您可以尝试使用数组map 方法：

let sorted_team_trends = q_id_arr.map( q => team_trends.find(t => t._id === q) );

假设这两个数组被定义为这样的字段：

let q_id_arr = [
        "5f86da2d37e3d200040ba523",
        "5f86b6ce37e3d200040ba4c6",
        "5ffc4abea04f3c0004e46cf3",
        ...
];

let team_trends = [
        {
                "_id" : "5f87e9d4554f370004ed178e",
                "positive" : 0.93,
                "engaged" : 0.558
        },
        {
                "_id" : "5f86e19037e3d200040ba534",
                "positive" : 0.585,
                "engaged" : 0.567
        },
        ...
]