Updated date field is not updated - mongodb

Question

I have defined this schema
var docSchema = mongoose.Schema({
name:{type:String,required:true},
}, { timestamps: { createdAt: 'createdAt',updatedAt:'updatedAt' }, collection : 'docs', discriminatorKey : '_type' });
I update the documents using this route
router.post('/:id', auth, function(req,res,next) {
var id = req.params.id;
docA.findByIdAndUpdate(id, req.body, {new: true}, function(err, doc) {
if(err)
res.json(err);
else if(doc==null)
res.status(404).send({
message: "Document not found"
});
else
res.json(doc);
});
});
I noticed updatedAt is not updated when I save some edits to the documents.
Besides this problem, thinking about it, it could be helpful to keep this data in form of array of updated date like:
updatedAt : [
"2016-10-25T12:52:44.967Z",
"2016-11-10T12:52:44.967Z",
"2016-12-01T12:52:44.967Z"
]
SOLUTION(?):According to #chridam suggestions, my current workaround to keep an array of update Dates is:
docSchema.pre(`findOneAndUpdate`, function(next) {
if(!this._update.updateHistory) {
console.log("findOneAndUpdate hook: updateHistory not present")
this._update.updateHistory=[];
}
this._update.updateHistory.push(new Date);
return next();
});
docSchema.pre('save', function (next) {
if(!this.updateHistory) {
console.log("Save hook: updateHistory not present")
this.updateHistory=[];
}
this.updateHistory.push(new Date);
next();
});

Answer 1

This is a known issue, please refer to the original thread on the plugin here, where dunnkers commented:
It's actually impossible to hook middleware onto update,
findByIdAndUpdate, findOneAndUpdate, findOneAndRemove and
findByIdAndRemove in Mongoose at the moment.
This means that no plugin is actually run when using any of these
functions.
Check out the notes section in the Mongoose documentation for
middleware. Issue Automattic/mongoose#964 also describes this.
As a suggested workaround, factoring in your schema changes:
var docSchema = mongoose.Schema({
"name": { "type": String, "required": true },
"updateHistory": [Date]
}, {
"timestamps": {
"createdAt": 'createdAt',
"updatedAt": 'updatedAt'
},
"collection" : 'docs',
"discriminatorKey": '_type'
});
router.post('/:id', auth, function(req,res,next) {
var id = req.params.id;
docA.findByIdAndUpdate(id, req.body, {new: true}, function(err, doc) {
if(err)
res.json(err);
else if(doc==null)
res.status(404).send({
message: "Document not found"
});
else {
doc.updateHistory.push(new Date());
doc.save().then(function(doc){
res.json(doc);
}, function(err) {
// want to handle errors here
})
}
});
});
Another approach would be to attach a hook to the schema:
docSchema.pre("findOneAndUpdate", function() {
this.updatedAt = Date.now();
});