Populate a single embedded document - node.js

Question

I have a user model that contains a single embedded document address that is defined like this:
let userSchema = new Schema({
id: ObjectId,
//...
address: {
type: AddressSchema,
required: true,
default: () => ({})
},
//...
});
const UserModel = mongoose.model('User', userSchema);
The Address contains a reference for a Country model:
let AddressSchema = new Schema({
country: {
type: Schema.Types.ObjectId,
ref: 'Country'
}
});
const AddressModel = mongoose.model('Address', AddressSchema);
Where the Country definition is:
let countrySchema = new Schema({
id: ObjectId,
name: {
type: String,
required: true,
unique: true
}
});
const CountryModel = mongoose.model('Country', countrySchema);
And this is how I am populating the user documents:
let user = await UserModel
.findByIdAndUpdate(
someId,
operators,
{ new: true }
)
.populate({
path: 'address.country',
model: CountryModel
})
When I am running a console.log(JSON.stringify(user.address)), the object is not well fetched, as you may see in the comment of the code below, there is an additional _id field that I don't know how to get rid of :
{
"country":{
"_id":{// ============> How to get rid of this _id field?
"_id":"5b56ecab8cba833c28e0e613",
"name":"USA",
"__v":0
}
}
There is something wrong either with my way of using the populate method or how I embed the Address schema in the User, but I am not able to figure it out

Answer 1

I found that the Address was saved in the user document in a way that does not help the populate method to retrieve the country
The JSON with which I was saving the address in the user was like that:
{
// Other fields of the user
address: {
country : {
_id: "5b56ecab8cba833c28e0e613"
}
}
}
But changing it to this form solved the problem:
{
// Other fields of the user
address: {
country : "5b56ecab8cba833c28e0e613"
}
}