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

Question

我正在执行两个MongoDB查询，然后我要同步结果数组，以确保它们处于相同的顺序。

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"
]

第二个数组是与问题id相关联的(20)个结果的集合:

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

下面是我使用的代码(下面是SO答案):

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

然而，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?任何建议都很感激!

更多细节:

在此步骤之前，我通过映射aggregate结果获得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object。

如何对对象进行排序?

Answer 1

修复问题的最终代码。

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. 如果你正在使用mongoose，那么它已经从聚合函数返回一个数组。
2. Mongoose使用MongoDB NodeJs原生驱动作为核心。在核心驱动中，ObjectId有一个函数.equals(otherId)。最好使用此函数进行id比较。

引用:

1. 比较mongoose _id和字符串
2. .aggregate(…)。toArray不是一个函数
3. https://mongodb.github.io/node-mongodb-native/api-bson-generated/objectid.html =

Answer 2

您可以使用数组的map方法来尝试:

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如下字段:

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
},
...
]