Return certain fields with .populate() from Mongoose

Question

I'm getting returned a JSON value from MongoDB after I run my query. The problem is I do not want to return all the JSON associated with my return, I tried searching the docs and didn't find a proper way to do this. I was wondering what if it is at possible, and if so what is the proper way of doing such. Example: In the DB

{
    user: "RMS",
    OS: "GNU/HURD",
    bearded: "yes",
    philosophy: {
        software: "FOSS",
        cryptology: "Necessary"
    },
    email: {
        responds: "Yes",
        address: "rms@gnu.org"
    },
    facebook: {}
}

{
    user: "zuckerburg",
    os: "OSX",
    bearded: "no",
    philosophy: {
        software: "OSS",
        cryptology: "Optional"
    },
    email: {},
    facebook: {
        responds: "Sometimes",
        address: "https://www.facebook.com/zuck?fref=ts"
    }
}

What would be the proper way of returning a field if it exists for a user, but if it doesn't return another field. For the example above I would want to return the [email][address] field for RMS and the [facebook][address] field for Zuckerburg. This is what I have tried to find if a field is null, but it doesn't appear to be working.

 .populate('user' , `email.address`)
  .exec(function (err, subscription){ 
    var key;
    var f;
    for(key in subscription){
      if(subscription[key].facebook != null  ){
          console.log("user has fb");
      }
    }
  }

score 122 · Accepted Answer · answered Nov 05 '14 at 20:09

122

I'm not completely clear on what you mean by "returning a field", but you can use a lean() query so that you can freely modify the output, then populate both fields and post-process the result to only keep the field you want:

.lean().populate('user', 'email.address facebook.address')
  .exec(function (err, subscription){ 
    if (subscription.user.email.address) {
        delete subscription.user.facebook;
    } else {
        delete subscription.user.email;
    }
  });

answered Nov 05 '14 at 20:09

JohnnyHK

305,182
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1

this not working for me, anyone knows if this has changed with an Mongoose update? – Ninja Coding Nov 10 '17 at 16:59
1

This is not working for me either, I tried `.populate('model', 'field')`, `.populate('model', { field: 1})`, `.populate('model', [field])` with and without `lean()` and with and without `selectPopulatedPaths: false` on the model but I always got the full populated object in the response. The documentation says your answer is supposed to be the right one but I can't make it work. Is somebody having the same issue ? – mel-mouk Nov 19 '19 at 13:55

dontmentionthebackup · Answer 2 · 2015-05-28T21:19:58.957

81

If you only want a few specific fields to be returned for the populated documents, you can accomplish this by passing the field name syntax as the second argument to the populate method.

Model
.findOne({ _id: 'bogus' })
.populate('the_field_to_populate', 'name') // only return the Persons name
...

See Mongoose populate field selection

edited May 28 '15 at 21:19

answered May 19 '15 at 09:02

dontmentionthebackup

2,775
1
21
18

13

Works fine. You can also returned more fields, only you must pass more fields. --> populate('the_field_to_populate', 'name lastname') – saeta Dec 16 '15 at 06:27
What if you had more than one model to populate and wanted fields for those? Like populate('users posts','name')? Would you get names for both? – MoDrags Mar 21 '17 at 16:40
Something like this: Model.findOne({_id: 'foo'}).populate({ path: 'parent-model', populate: { path: 'someProperty', populate: { path: 'somePropertyBelow' } } }) – dontmentionthebackup Mar 28 '17 at 13:05

score 57 · Answer 3 · answered Jun 12 '17 at 22:40

57

Try to do this:

applicantListToExport: function (query, callback) {
  this
   .find(query).select({'advtId': 0})
   .populate({
      path: 'influId',
      model: 'influencer',
      select: { '_id': 1,'user':1},
      populate: {
        path: 'userid',
        model: 'User'
      }
   })
 .populate('campaignId',{'campaignTitle':1})
 .exec(callback);
}

answered Jun 12 '17 at 22:40

Naveen Kumar

987
11
11

4

Just to explain a little bit what's happening here: This is to select fields in a nested populate and in a simple populate. – Andre Simon Feb 26 '19 at 23:23
You saved my day :) – Peshraw H. Ahmed May 09 '19 at 13:22

score 29 · Answer 4 · answered Nov 02 '14 at 11:42

29

Try to do this:

User.find(options, '_id user email facebook').populate('facebook', '_id pos').exec(function (err, users) {

answered Nov 02 '14 at 11:42

scuencag

664
4
11

score 28 · Answer 5 · answered May 16 '16 at 19:20

28

Now what you can do is :

  .populate('friends', { username: 1, age: 1})

answered May 16 '16 at 19:20

Scaraux

3,841
4
40
80

score 14 · Answer 6 · answered Aug 07 '20 at 17:26

14

In the following query i retrieved articles which match the condition show=true the retrieved data title and createdAt also retrieve the category of article only the title of category and it's id.

let articles = await articleModel
        .find({ show: true }, { title: 1, createdAt: 1 })
        .populate("category", { title: 1, _id: 1 });

answered Aug 07 '20 at 17:26

Ahmed Mahmoud

1,724
1
17
21

Simple and elegant – Phantom007 Apr 01 '21 at 10:28

score 8 · Answer 7 · edited May 23 '21 at 23:49

8

for a single level populate you can use -> populate('user','name email age')

for nested population

populate({
    path:'posts',
    populate({
         path:'user'
         select:'name email age'
    })
})

edited May 23 '21 at 23:49

phsource

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answered May 23 '21 at 13:34

Sumit Garg

91
1
1

score 4 · Answer 8 · answered Mar 21 '19 at 12:59

4

you to try :

Post.find({_id: {$nin: [info._id]}, tags: {$in: info.tags}}).sort({_id:-1})
.populate('uid','nm')
.populate('tags','nm')
.limit(20).exec();

answered Mar 21 '19 at 12:59

Tran Hoang Hiep

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5
12

score 4 · Answer 9 · answered Jan 15 '22 at 12:29

I was stuck on this issue. I wanted to populator and user field linked to the Blog Post. Using populate only returned everything including the password. By specifying fields as an array it works fine.

//code emitted for brevity

await Blog.findById(ID).populate("author", ["firstName", "lastName", 
"profilePicture", "_id"])

//

This is the result of the response

score 2 · Answer 10 · answered Mar 13 '20 at 20:59

2

Just to complement the answers above, if you want to include everything but only exclude certain attributes, you can do the following:

.populate('users', {password: 0, preferences: 0})

answered Mar 13 '20 at 20:59

Prashant Ghimire

4,890
3
35
46

score 0 · Answer 11 · answered Aug 21 '19 at 04:24

0

you can try using below,

 Model
    .find()
    .populate({path: 'foreign_field', ['_id', 'name']}) // only return the Id and Persons name
    ...

answered Aug 21 '19 at 04:24

Naresh Ramoliya

770
2
8
25

1

This is the way I implemented it too. populate("author", ["firstName", "lastName", "profilePicture", "_id"]) And it works like a charm – Fabrice Hafashimana Jan 15 '22 at 12:24

score 0 · Answer 12 · edited Apr 07 '20 at 08:46

Hi for me it worked for me i populated user field using the populate code : --->

async function displayMessage(req,res,next){
    try{
        let data= await Msg.find().populate("user","userName userProfileImg","User")
               if(data===null) throw "Data couldn ot be loaded server error"
        else {
            res.status(200).json(data)
        }
    }   catch(err){
            next(err)
    }
}

i am directly getting the result . Here the fields userName , userProfile image are the ones that ive required selectively and the syntax for populate is :-->

 .populate("user field to populate","fields to display with spaces between each of them " , "modelName ")

every parameter should be in inverted comma's.

Below is the output i recieve.One more thing you don't have to worry about the populating sub-document id you will automatically get them.

[
    {
        "_id": "5e8bff324beaaa04701f3bb9",
        "text": "testing message route",
        "user": {
            "_id": "5e8bf062d3c310054cf9f293",
            "userName": "boss",
            "userProfileImg": "img"
        },
        "__v": 0
    },
    {
        "_id": "5e8bff8dd4368a2858e8f771",
        "text": "testing message route second",
        "user": {
            "_id": "5e8bf062d3c310054cf9f293",
            "userName": "boss",
            "userProfileImg": "img"
        },
        "__v": 0
    },
    {
        "_id": "5e8c0c08e9bdb8209829176a",
        "text": "testing message route second",
        "user": {
            "_id": "5e8bf062d3c310054cf9f293",
            "userName": "boss",
            "userProfileImg": "img"
        },
        "__v": 0
    },
    {
        "_id": "5e8c0e0bcb63b12ec875962a",
        "text": "testing message route fourth time",
        "user": {
            "_id": "5e8bf062d3c310054cf9f293",
            "userName": "boss",
            "userProfileImg": "img"
        },
        "__v": 0
    }
]

score 0 · Answer 13 · answered Mar 30 '23 at 22:56

0

I tried with:

.populate('model', { field_1: 1, field_2: 1 }).exec()...

answered Mar 30 '23 at 22:56

Dante Cervantes

1

score 0 · Answer 14 · answered Aug 04 '23 at 14:20

To populate multiple fields using findOne.

For example, this is your model

const productSchema = new mongoose.Schema(
    {
        user: {
            type: mongoose.Schema.Types.ObjectId,
            required: true,
            ref: "User",
        },
        store: {
            type: mongoose.Schema.Types.ObjectId,
            required: true,
            ref: "Store",
        },
        name: {
            type: String,
            required: true,
        },
    },
);

const Product = mongoose.model("Product", productSchema);

export default Product;

To populate store and user without using path, do this:

await Product.findOne({ name: "dancing shoe" }).populate("user store");

The next params will return a specific field in the populated models or just the _id where the field doesn't exist. In other words, the second params is used as select.

await Product.findOne({ name: "dancing shoe" }).populate("user store", "name");

This will populate user and store model with _id and name only

Return certain fields with .populate() from Mongoose

14 Answers14

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