Node.js 在nodejs mongodb中按id查找文档

所以我想通过id查找一个特定的文档，例如

[
{
"_id": "5d0381ad681a2a3aa1dc5872",
"role_num": 1,
"first_name": "Adilf",
"last_name": "Adli",
"marks": 97
},
{
"_id": "5d0381ad681a2a3aa1dc5873",
"role_num": 2,
"first_name": "Mario",
"last_name": "Adl",
"marks": 93
},
{
"_id": "5d0381ad681a2a3aa1dc5874",
"role_num": 3,
"first_name": "Adi",
"last_name": "Ad",
"marks": 89
},
{
"_id": "5d0381ad681a2a3aa1dc5875",
"role_num": 4,
"first_name": "Harold",
"last_name": "Nome",
"marks": 78
},
{
"_id": "5d10b6124adac42c4467cb88",
"role_num": 6,
"first_name": "Mohammed",
"last_name": "Khan",
"marks": 91
},
{
"_id": "5d10b65f4adac42c4467cb89",
"role_num": 6,
"first_name": "Mohammed",
"last_name": "Khan",
"marks": 91
},
{
"_id": "5d10ebc562562921883741a1",
"role_num": 6,
"first_name": "Mohammed",
"last_name": "Khan",
"marks": 91
},
{
"_id": "5d11af3a62562921883741a3",
"role_num": 6,
"first_name": "Mohammed",
"last_name": "Khan",
"marks": 91
},
{
"_id": "5d11b40b62562921883741a4",
"role_num": 6,
"first_name": "Mohammed",
"last_name": "Khan",
"marks": 91
},
{
"_id": "5d11b4cd6dc8db0fe0f489fc",
"role_num": 7,
"first_name": "Masrur",
"last_name": "Ahmed",
"marks": 81
},
{
"_id": "5d11b5131beb7f338414bc96",
"role_num": 7,
"first_name": "Masrur",
"last_name": "Ahmed",
"marks": 81
},
{
"_id": "5d11b56cd0baff00cc616ebb",
"role_num": 7,
"first_name": "Masrur",
"last_name": "Ahmed",
"marks": 81
},
{
"_id": "5d11b586d76c463d30d02355",
"role_num": 7,
"first_name": "Masrur",
"last_name": "Ahmed",
"marks": 81
},
{
"_id": "5d11b74effe56935d88d910e",
"role_num": 7,
"first_name": "Masrur",
"last_name": "Ahmed",
"marks": 81
},
{
"_id": "5d11b7d1e425ab1dbceda262",
"role_num": 7,
"first_name": "Masrur",
"last_name": "Ahmed",
"marks": 81
},
{
"_id": "5d11b90e44b2c61650377951",
"role_num": 7,
"first_name": "Masrur",
"last_name": "Ahmed",
"marks": 81
},
{
"_id": "5d120883a2f4d83bac8441c7",
"first_name": "Maria"
},
{
"_id": "5d1208cca2f4d83bac8441c8",
"first_name": "Maria"
},
{
"_id": "5d12093fa2f4d83bac8441c9",
"first_name": "Maria"
},
{
"_id": "5d1209c0a2f4d83bac8441ca",
"first_name": "Baki"
},
{
"_id": "5d120f0ed9e07909a413cd85",
"role_num": "5",
"first_name": "Arojfsdof",
"last_name": "adfjaf",
"marks": "12"
},
{
"_id": "5d12fff7d9e07909a413cd8a",
"role_num": "17",
"first_name": "BARKS",
"last_name": "DUDUE",
"marks": "45"
},
{
"_id": "5d131c42313e183ae09966c3",
"role_num": "4",
"first_name": "Maam",
"last_name": "Alsad",
"marks": "80"
}
]

上面我有一个学生列表，我想用get方法通过id找到一个特定的学生，例如，让我们假设我想找到这个

{
    "_id": "5d131c42313e183ae09966c3",
    "role_num": "4",
    "first_name": "Maam",
    "last_name": "Alsad",
    "marks": "80"
}

这是我的“查找id”代码，让我知道我必须修复什么

second.get('/students/:id', (req, res) => {
   db.collection('students').find({"_id": ObjectID(req.body._id)}).toArray((err,result) => {
     if(!err) {
        res.send(result);
     } else {
         console.log(err);
     }

   });
});

---

在我使用findOne方法之前，但它只用于查找第一个doucment的发生，而这不是我从Mongo获取ID为db.collection（'students'）的记录所要查找的内容。findOne（{u ID:：ID}）是正确的格式。您只能获取一条记录，因为您不能有两条ID相同的记录。

缺少

新的

var ObjectID = require('mongodb').ObjectID;   

db.collection('students').find({"_id": new ObjectID(req.body._id)})

---

@因此，如果我想在我的代码中找到{“_id”：“5D0381AD681AA3AA1DC5874”，“role_num”：3，“first_name”：“Adi”，“last_name”：“Ad”，“marks”：89}，@franiis我可以在代码中更改什么，我不想硬编码值我不是Node.js开发者。通过

id

查询数据库是数据库通信中最重要的任务。可能是这样的：（我肯定有一些例子）。我在哪里定义像“_id”：idMine是异步函数的一部分：

let client=wait MongoClient.connect（uri，{useNewUrlParser:true}）；设db=client.db（“学生”）；try{const res=await db.collection（'students'）。findOne（{“\u id”：id}）；//用response做一些事情

同样的事情也可以不用async:

db.collection（'students'）。findOne（{“id”：id}，函数（err，result）{//handle result and error}）