Mongoose : Can't populate after find to make $near query - node.js

Question

I am trying to populate user informations to get his location but i am getting undefined.
Here are my schemas:
AnnounceSchema:
const AnnounceSchema = new mongoose.Schema({
titre: String,
contenu: String,
image: String,
tag: String,
media: String,
date: {
type: Date,
default: Date.now
},
commentaires: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Comment' }],
authorId: { type: mongoose.Schema.Types.ObjectId, ref: 'User' }
})
UserSchema:
const UserSchema = new mongoose.Schema({
username: { type: String, required: true, unique: true },
password: { type: String, required: true },
email: { type: String, required: true, unique: true },
loc: { type: { type: String, default: 'Point' }, coordinates: { type: [Number] } }
});
UserSchema.index({ loc: '2dsphere' });
And here is my query :
Announce.find({})
.populate('authorId', null,
{
'authorId.loc': {
$near: {
$geometry: {
type: 'Point',
coordinates: [req.user.loc.coordinates[0], req.user.loc.coordinates[1]]
},
$maxDistance: 10000
}
}
})
.exec((err, announces) => {
if (err) {
res.send(err)
} else {
res.render('announce/search', { announces: announces })
}
})
The error I'm getting is "unable to find index for $geoNear query". I've added an index to the AnnonceSchema but no change:
AnnonceSchema.index({ "authorId.loc" : "2dsphere"})

Answer 1

This should work:
Announce.find({})
.populate('author',
{
path : 'authorId',
match: {
'loc': {
$near: {
$geometry: {
type: 'Point',
coordinates: [req.user.loc.coordinates[0], req.user.loc.coordinates[1]]
},
$maxDistance: 10000
}
}
},
model: 'User',
})
.exec((err, announces) => {
if (err) {
res.send(err)
} else {
res.render('announce/search', { announces: announces })
}
})
populate works in two ways
it can populate by reference Announce.find({}).populate('authorId')
or by a custom query (which is what you need)