在MongoDB中按ID查找返回null [英] Finding by id in MongoDB returns null

问题描述

我对NodeJS和MongoDB

我正在尝试做一个非常基本的东西，但是它似乎没有用.
我确定我在某处缺少东西.

I am trying to do a very basic stuff but it does not seem to be working.
I am sure that I am missing something somewhere.

基本上，我正在尝试根据ID从数据库中查找用户.
这是我的代码:

Basically, I am trying to find a user from the DB based on the id.
Here is my code:

function findUser(id, cb) {
    MongoClient.connect(cs, function(err, db) {
        var col = db.collection('users');
        col.findOne({ _id: id }, function(err, user) {
            // Value of user here is always null
            // However, if I manually check the database, 
            // I can clearly see that the user with the 
            // same id does exists.
            return cb(err, user);
        });
    });
}

推荐答案

我假设您的id类型为string

在这种情况下，您需要将其转换为适当的Mongo ObjectID

If this is the case, you need to convert it to a proper Mongo ObjectID

尝试此代码:

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

function findUser(id, cb) {
    MongoClient.connect(cs, function(err, db) {
        var col = db.collection('users');
        col.findOne({ _id: new ObjectID(id) }, function(err, user) {
            return cb(err, user);
        });
    });
}

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