Mongoose Populate not working - node.js

Question

Hello i have this Schema(called schema.js):
var mongoose = require('mongoose'),
Schema = mongoose.Schema;
var RoomSchema = new Schema({
name: { type: String, required: true, index: { unique: true } },
people: { type: Number, required: true },
childrens: {type: Number, required: true},
total: {type: Number, required: true}
});
var Room = mongoose.model('Room', RoomSchema);
var AvSchema = new Schema({
roomId: {type: Schema.Types.ObjectId, ref: 'Room'},
people: { type: Number, required: true },
childrens: {type: Number, required: true},
total: {type: Number, required: true}
});
var Av = mongoose.model('Av', AvSchema);
module.exports = {
Room: Room,
Av: Av
};
in my Route file :
module.exports = function(app) {
var model = require('../models/Schema');
app.get('/api/rooms', function(req, res) {
model.Room.find(function(err, rooms) {
if (err)
res.send(err);
res.json(rooms);
});
});
app.get('/api/av', function(req, res) {
model.Av.find().populate('roomId').exec(function(err, av) {
if (err)
res.send(err);
res.json(av);
});
});
};
A pic of the db :
GET /api/rooms - response:
[{
"_id": "5444d0dd9a31437167eea816",
"name": "Single",
"people": 1,
"childrens": 1,
"total": 4
}, {
"_id": "5444d1009a31437167eea817",
"name": "Double",
"people": 2,
"childrens": 2,
"total": 10
}]
When i call api/rooms looks fine but when i call api/av i got an empty array [] .... Any idea what i do wrong? I should mention that i have inserted records in av collection for both roomsID
Thank you in advance.

Answer 1

By default, Mongoose pluralizes the model name to come up with the name of the collection, so Mongoose is looking in the avs collection instead of av.
You can explicitly set the collection name by passing that as the third parameter to model:
var Av = mongoose.model('Av', AvSchema, 'av');

Answer 2

I had the same issue but none of the answers worked for me.
I wanted to populate a document after it was queried.
This didn't work:
// IIFE for async/await
( async() => {
var user = await User.findOne( { _id } );
await user.populate( 'comments' ); // Doesn't work
} );
The Mongoose Documentation explains that when calling .populate() without a callback it won't be executed. Instead you need to use .populate().execPopulate():
// IIFE for async/await
( async() => {
var user = await User.findOne( { _id } );
await user.populate( 'comments' ).execPopulate(); // Works as expected
} );

Answer 3

Similar to CodyBugstein's answer, I'm posting why it wasn't working in my case, even though it's not the same case as OP's.
I was trying to populate the "pro" field of my schema in a .post('save') hook, as so:
mySchema.post('save', function(doc, next) {
console.log(doc.pro); // Expected to log ObjectID
doc.populate("pro"); // Populate field
console.log(doc.pro); // Expected to log actual pro document
}
However, the 2nd console.log was also logging the ObjectID instead of the doc.
After struggling with this for a solid hour and trying different approaches, I found out that all I had to do was use promises and call execPopulate() so that it returned a fully-fledged promise. I used async/await but you could use .then too:
mySchema.post('save', async function(doc, next) {
console.log(doc.pro); // Expected to log ObjectID
await doc.populate("pro").execPopulate(); // Populate field
console.log(doc.pro); // Expected to log actual pro document
}
This way, the 2nd console.log did log the entire pro doc as expected :)

Answer 4

Since this is the most popular result for the query
mongoose populate not working
I'll include the reason it wasn't working for me, even though it's not a direct answer to this already solved question, in the hopes it will help someone
The problem for me was that I had specified fields in select({..} but not the field I was trying to populate.

Answer 5

Don't forget to add the ref property to the schema for the property you are trying to populate. E.g.
// ...
const orderSchema = new mongoose.Schema({
userId: {
type: Types.ObjectId,
required: true
},
reservationId: {
type: Types.ObjectId,
required: true,
ref: 'Reservation' // <-- don't forget the ref
}
}, {
timestamps: true
})
// ...
See Mongoose Populate

Answer 6

Also check that your schema doesn't have depopulate in toJSON or toObject option set to true. (facepalm myself)
See all schema options

Answer 7

For me, it is was due to incorrect data. The Ids which I want to populate got deleted from the main table.
So when I do populate it didn't filled the populated data because the Ids were not in the table.

Answer 8

add this in your model
const productSchema = mongoose.Schema(
{
name: {
type: String,
required: [true, "product name must be provide"],
minlength: [3, "Name length minimum is 3"],
maxlength: [50, "Name length maximum is 50"],
trim: true,
},
price: {
type: Number,
required: [true, "price must be provide for product"],
default: 0,
},
description: {
type: String,
required: [true, "product description is required"],
trim: true,
},
{
timestamps: true,
toJSON: {
virtuals: true,
},
toObject: {
virtuals: true,
},
}
);
Example:
productSchema.virtual("reviews", {
ref: "Review",
localField: "_id",
foreignField: "product",
justOne: false,
});
How to use:
products = await productModel.find({}).populate("reviews");

Answer 9

For me, the issue was that I did not require the model to be populated at the beginning of the file.