findByIdAndUpdate overwrites existing value - node.js

Question

facing a small issue that whenever I try to update a 'comments' property it automatically overwrites old property, doesn't add next value to the array. Tried many options like adding $set parameter as option, removing it, adding overwrite: false, but not successfully. Been looking at the docs, but feels like I'm something missing and even docs can't help me.
My Model:
const mongoose = require("mongoose");
const TicketSchema = new mongoose.Schema({
title: {
type: String,
minlength: 5,
maxlength: 50,
required: [true, "Please validate title"]
},
description: {
type: String,
minlength: 10,
maxlength: 200,
required: [true, "Please validate description"]
},
comments: {
type: Array,
default: []
},
status: {
type: String,
enum: ["in progress", "resolved", "pending"],
default: "pending",
},
priority: {
type: String,
enum: ["regular", "medium", "high"],
default: "regular"
},
createdBy: {
type: mongoose.Types.ObjectId,
ref: "User",
required: [true, "Please provide user"],
}
}, {
timestamps: true,
});
module.exports = mongoose.model('Ticket', TicketSchema);
My controller:
const updateUser = async (req, res) => {
const {
body: {username, email, firstname, lastname, country, password, comments},
params: {
id: employeeId
}
} = req;
const user = await User.findByIdAndUpdate(employeeId, req.body, {
$set: {
comments: req.body.comments
}
}, {
new: true, runValidators: true, upsert: true
}).select(["-password"]);
// Don't allow IT users to change credentials for IT and ADM users.
if (user.type.startsWith("IT") || user.type.startsWith("ADM")) throw new NotFoundError(`No user with id ${employeeId}`);
if (!user) throw new NotFoundError(`No user with id ${employeeId}`);
res.status(StatusCodes.OK).json({user});
};

Answer 1

You may want to use $push operator instead of $set.
Assuming req.body.comments is an array with comments, you could use $each to construct something like this:
const user = await User.findByIdAndUpdate(employeeId, req.body, {
$push: {
comments: { $each: req.body.comments }
}, {
new: true, runValidators: true, upsert: true
}
}).select(["-password"]);