How to retrieve specific queried array collections in MongoDB using NodeJS

Question

I've just tried MongoDB & NodeJS and having issue in finding specific array collections using Nodejs.

Here's the the collections I have :

    {
  "_id": ObjectId("552aa4da6e25e57ebde7ac6f"),
  "username": "blablabla",
  "email": "xxx@gmail.com",
  "password": "Dummy Trip",
  "itinerary": [
    {
      "_id": ObjectId("552c109adb616795044a919e"),
      "title": "test-0",
      "desc": "test-0-desc"
    },
    {
      "_id": ObjectId("552c10b0db616795044a91a0"),
      "title": "test-1",
      "desc": "test-1-desc"
    },
    {
      "_id": ObjectId("552c1128db616795044a91a1"),
      "title": "test-2",
      "desc": "test-2-desc"
    }
  ]
}

So I need to find the array of itinerary that has objecId of "552c109adb616795044a919e"

In MongoDB terminal I use findOne command & positional $ operator and it works as expected, showing only the array I search for.

Command :

db.user.findOne({ "itinerary._id" : ObjectId("552c109adb616795044a919e") }, {"itinerary.$" : 1})

Result :

{
"_id" : ObjectId("552aa4da6e25e57ebde7ac6f"),
"itinerary" : [
    {
        "_id" : ObjectId("552c109adb616795044a919e"),
        "title" : "test-0",
        "desc" : "test-0-desc"
    }
]}

But why when I tried to implement it in NodeJS, it shows all records instead of the specific array I search.

Here's my NodeJS :

  var userCollection = db.get('user'); userCollection.findOne({ "itinerary._id" : new ObjectID("552c109adb616795044a919e") }, {"itinerary.$" : 1},function(e,userDocs){ console.log(userDocs); }); 

NodeJS Result (Showing all results) :

 { _id: 552aa4da6e25e57ebde7ac6f, username: 'blablabla', email: 'xxx@gmail.com', password: 'Dummy Trip', itinerary: [ { _id: 552c109adb616795044a919e, title: 'test-0', desc: 'test-0-desc' }, { _id: 552c10b0db616795044a91a0, title: 'test-1', desc: 'test-1-desc' }, { _id: 552c1128db616795044a91a1, title: 'test-2', desc: 'test-2-desc' } ] } 

Did I miss something here ?

Note :

• I'm using Node MongoDB native driver

Thanks in advance :)

Answer 1

I am assuming your itinerary is an array. then you will have to use $elemMatch in mongodb.More details on elemMatch .

You can try something like.

 var userCollection = db.get('user');
 userCollection.findOne({ "itinerary": { $elemMatch: {_id: new ObjectID("552c109adb616795044a919e")}}}, {"itinerary.$" : 1},function(e,userDocs){
console.log(userDocs);
});

Also i think for matching object id you can use mongoose.Types.ObjectId("552c109adb616795044a919e")