Add unique id to nested array in user model Mongoosedb - node.js

Question

Im trying to add a unique track id to a nested array in user favourites array inside the user model. New to this, so a little help would be great
User.js (model)
var UserSchema = new Schema({
name: String,
username: { type: String, required: true, index: { unique: true }},
password: { type: String, required: true, select: false },
favorites: [Track],
meta : [{
favorites_count : {
type: Number,
default: 0
},
friends_count: {
type: Number,
default: 0
}
}]
});
apiRouter.route('/users/:user_id/favorites/:track_id')
.post(function(req, res){
User.findByIdAndUpdate(req.params.user_id, {
$addToSet: {"favorites": {track_id: req.body.track_id}},
$inc: { "meta.favorites_count": 1 }
// $set: { "meta.favorites_count": 1}
},
{safe: true, upsert: true}, function(err, user) {
if (err) res.send(err);
res.json({ message: "Track Favorited" });
}
);
})

Answer 1

You should define your favorites in your schema like the following:
var mongoose = require('mongoose'),
ObjectId = mongoose.Types.ObjectId;
var UserSchema = new Schema({
name: String,
username: { type: String, required: true, index: { unique: true }},
password: { type: String, required: true, select: false },
favorites: [{ type : ObjectId, ref: 'Track' }],
meta : [{
favorites_count : {
type: Number,
default: 0
},
friends_count: {
type: Number,
default: 0
}
}]
});
And change your route to:
apiRouter.route('/users/:user_id/favorites/:track_id')
.post(function(req, res){
User.findByIdAndUpdate(req.params.user_id, {
$addToSet: {"favorites": req.body.track_id},
$inc: { "meta.favorites_count": 1 }
// $set: { "meta.favorites_count": 1}
},
{safe: true, upsert: true}, function(err, user) {
if (err) res.send(err);
res.json({ message: "Track Favorited" });
}
);
});
EDIT: Answer the question from your comments.
If the track id is already present in your favorites array then you should change the your query to like this:
var track_id = req.body.track_id;
User.findOneAndUpdate({
_id: req.params.user_id,
favorites: {$nin: [track_id]}
},{
$addToSet: {"favorites": track_id },
$inc: { "meta.favorites_count": 1 }
// $set: { "meta.favorites_count": 1}
},{
safe: true,
upsert: true
},function(err, user) {
if (err) res.send(err);
res.json({ message: "Track Favorited" });
}
);
So you should exclude your documents that already contains track_id in favorites array