Mongoose populate returning empty array

Question

I am trying to use mongoose populate function but in response I am getting empty array, I have seen multiple posts regarding this

var MerchantSchema = new mongoose.Schema({
  packages: [{ $type: mongoose.Schema.Types.ObjectId, ref: 'Package'}]
},
{
    typeKey: '$type',
    timestamps: { createdAt: 'created_at', updatedAt: 'updated_at'}
});

module.exports = mongoose.model('Merchant', MerchantSchema);

This is my schema definition for the base model.

var mongoose = require('mongoose');

var PackageSchema = new mongoose.Schema({
    merchant_id: { type: mongoose.Schema.Types.ObjectId, ref: 'Merchant' },
    name: String,
    original_price: Number,
    discounted_price: Number
});

module.exports = mongoose.model('Package', PackageSchema);

And this is the model I am referring to. The data inside the Package model and Merchant model is being saved just fine.

Merchant document

Package document

But if I query using populate function I am being returned an empty string

Merchant
.findById( req.params.id, 'packages')
.populate('packages')
.exec(function (err, merchant) {
    if (err)
        next(err);
    else
        res.status(200).json(merchant);
});

Output:

{
  "_id": "579b3b2dc2e8d61c0ecd2731",
  "packages": []
}

Can anyone help me

Update:

Ok something really odd is happening. If I try to populate the Package document with merchant_id it is working but not the other way around.

Package
    .find()
    .populate('merchant_id')
    .exec(function (err, packages) {
        if(err)
            next(err);
        else
            res.status(200).json(packages);
    });

Output:

[
  {
    "_id": "579b3b51c2e8d61c0ecd2732",
    "name": "Hair + Nails",
    "original_price": 600,
    "discounted_price": 400,
    "merchant_id": {
      "_id": "579b3b2dc2e8d61c0ecd2731",
      "updated_at": "2016-07-29T11:17:37.474Z",
      "created_at": "2016-07-29T11:17:01.216Z",
      "name": "VLCC",
      "logo_image": "http://vlccwellness.com/India/wp-content/uploads/2015/09/logo1.png?",
      "cover_image": "http://image3.mouthshut.com/images/imagesp/925053993s.jpg?",
      "__v": 1,
      "tags": [],
      "packages": [
        "579b3b51c2e8d61c0ecd2732"
      ],
      "work_hours": {
        "opening_time": 1000,
        "closing_time": 2100,
        "holiday": "Sunday"
      },
      "information": {
        "description": "Lorem Ipsum",
        "gender": "Men",
        "services": [
          "Hair"
        ],

I'm having this same exact problem, but my models look just like yours. What was the fix in the end? type is not my problem. — TheValyreanGroup
– TheValyreanGroup, Commented Mar 14, 2018 at 16:33

Azeem Malik · Accepted Answer · 2016-07-29 12:52:48Z

2

Use type insted of $type in MerchantSchema.

var MerchantSchema = new mongoose.Schema({
  packages: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Package'}]
},
{
    typeKey: '$type',
    timestamps: { createdAt: 'created_at', updatedAt: 'updated_at'}
});

module.exports = mongoose.model('Merchant', MerchantSchema);

Verify there is an array of ObjectId against packages in your Merchant document.

edited Jul 29, 2016 at 12:52

answered Jul 29, 2016 at 12:47

Azeem Malik

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2 Comments

TheValyreanGroup Over a year ago

I'm having the same problem. But my model is using type not $type.

Azeem Malik Over a year ago

@TheValyreanGroup check your ref type it should be same as model name .

Arun Ghosh · Accepted Answer · 2016-07-29 12:03:01Z

0

Can you try by removing second parameter from the findBbyId:

Merchant
.findById( req.params.id)
.populate('packages')
.exec(function (err, merchant) {
    if (err)
        next(err);
    else
        res.status(200).json(merchant);
});

answered Jul 29, 2016 at 12:03

Arun Ghosh

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1 Comment

Parichit Over a year ago

Tried that, still getting an empty array

jofftiquez · Accepted Answer · 2016-07-29 20:01:53Z

0

Well because your packages field on your Schema is an array you should populate it as an array as well.

Try

.populate([
    {path:'packages', model:Package}
])

wher Package is the instance of your Package Model.

answered Jul 29, 2016 at 20:01

jofftiquez

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Comments

frane · Accepted Answer · 2016-08-02 15:31:24Z

0

Make sure that packages array in Merchant schema contains ObjectIds of type string, (not number). You can ensure this with something like:

merchant.packages.map(r => { r._id = r._id + ''; });

answered Aug 2, 2016 at 15:31

frane

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