NodeJS + MongoDB: Getting data from collection with findOne ()

Question

I have a collection "companies" with several objects. Every object has "_id" parameter. I'm trying to get this parameter from db:

app.get('/companies/:id',function(req,res){
db.collection("companies",function(err,collection){
    console.log(req.params.id);
    collection.findOne({_id: req.params.id},function(err, doc) {
        if (doc){
            console.log(doc._id);
        } else {
            console.log('no data for this company');
        }
    });
});
});

So, I request companies/4fcfd7f246e1464d05000001 (4fcfd7f246e1464d05000001 is _id-parma of a object I need) and findOne returns nothing, that' why console.log('no data for this company'); executes.

I'm absolutely sure that I have an object with _id="4fcfd7f246e1464d05000001". What I'm doing wrong? Thanks!

However, I've just noticed that id is not a typical string field. That's what mViewer shows:

"_id": {
        "$oid": "4fcfd7f246e1464d05000001"
    },

Seems to be strange a bit...

That's an ObjectId. In your query you should construct one from the string (I'm surprised that the library doesn't do it for you). — Sergio Tulentsev, Jun 07 '12 at 10:00

score 21 · Accepted Answer · edited May 23 '17 at 11:46

21

You need to construct the ObjectID and not pass it in as a string. Something like this should work:

var BSON = require('mongodb').BSONPure;
var obj_id = BSON.ObjectID.createFromHexString("4fcfd7f246e1464d05000001");

Then, try using that in your find/findOne.

Edit: As pointed out by Ohad in the comments (thanks Ohad!), you can also use:

new require('mongodb').ObjectID(req.params.id)

Instead of createFromHexString as outlined above.

edited May 23 '17 at 11:46

Community

1
1

answered Jun 07 '12 at 10:06

Adam Comerford

21,336
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I tried var obj_id = BSON.ObjectID.createFromHexString(req.params.id); collection.findOne({_id : obj_id},function(err, doc) { And it worked - thank you very much! – f1nn Jun 07 '12 at 10:15
4

You can use "new require('mongodb').ObjectID(req.params.id)" instead of createFromHexString – Ohad Kravchick Oct 24 '12 at 13:35
@OhadKravchick works like a charm. I would also up vote if it was an answer – Pith Jul 03 '13 at 09:29

score 3 · Answer 2 · answered Jun 07 '12 at 10:25

That's because _id field in mongo isn't of string type (as your req.params.id). As suggested in other answers, you should explicitly convert it.

Try mongoskin, you could use it like node-mongodb-native driver, but with some sugar. For example:

// connect easier
var db = require('mongoskin').mongo.db('localhost:27017/testdb?auto_reconnect');

// collections
var companies = db.collection('companies');

// create object IDs
var oid = db.companies.id(req.params.id);

// some nice functions…
companies.findById();

//… and bindings
db.bind('companies', {
  top10: function(callback) {
    this.find({}, {limit: 10, sort: [['rating', -1]]).toArray(callback);
  } 
});

db.companies.top10(printTop10);

score 1 · Answer 3 · answered Sep 03 '13 at 11:01

1

You can use findById() which will take care of the id conversion for you.

company = Company.findById(req.params.id, function(err, company) {
    //////////
});

answered Sep 03 '13 at 11:01

darren

18,845
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1

What is Company in this case? What is findById? Can you link to the documentation? Thanks! – ryanm Sep 29 '15 at 15:44

score 0 · Answer 4 · answered May 22 '20 at 19:04

In case these didn't work for you, this worked for me for accessing a blog post:

const getSinglePost = async (req, res) => {

    let id = req.params.id;
    var ObjectId = require('mongodb').ObjectId;
    const db = await client.db('CMS');

    const data = await db.collection("posts").findOne({ _id: ObjectId(id) })

    if (data) {
        res.status(200).send(data)
    } else res.status(400).send({ message: "no post found" })

}

NodeJS + MongoDB: Getting data from collection with findOne ()

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