Mongoose: MongoError: >1 field while trying to project out $elemMatch - mongodb

Question

I'm trying to project out only the matched element of an array, in the updated version. But I'm getting the error: "MongoError: >1 field in obj: { _id: 0, lotes.$: 1 }"
If I remove 'new: true', it works. But then I have the doc before the update. And I would really like the updated version.
What's wrong? How can I fix it?
The Offer doc is something like:
{
_id
series: [ Serie ]
}
Serie structure is something like:
{
_id
public.available: Number
public.expDate: Date
}
I'm using Mongoose:
var query = {
'_id': offerId,
'series': {
$elemMatch: {
'_id': serieId,
'public.available': {$gt:0},
'public.expDate': {$gt: now}
}
}
};
var update = {
$inc: { 'series.$.public.available' : -1 }
};
var options = { // project out just the element found, updated
new:true,
select: {
'_id': 0,
'series.$': 1
}
};
Offers.findOneAndUpdate(query, update, options)
.then( element => {
...
}

Answer 1

For anyone else experiencing this error, it is also the most common error when trying to perform an illegal action such as trying to update a database element inside of a findOne request.
Making sure your request is correct, such as findOneAndUpdate should be your first port of call when you get this error.

Answer 2

As Anthony Winzlet pointed out in the links, there seems to be an issue with Mongoose, in which if you use 'new:true', you can't project out the $elemMatch.
So my solution was to keep using 'new:true' only, without projections. And reduce the array later on to get the $elemMatch:
.then( (result) => {
var aux = result.series.reduce((acu, serie, index) => {
if (serie._id == req.params.serieId) return index;
});
var element = result.series[aux];
}