model.update() not updating - node.js

Question

I'm trying to add a new element to an array.
This is the code:
var findEditThenSave = function(personId, done) {
var foodToAdd = 'hamburger';
var foodArray = [];
Person.findById(personId, function (err, data) {
if (err) return console.log(err);
done(null, data);
foodArray = data.favoriteFoods;
console.log("foodArray inside findById: ", foodArray);
foodArray.push(foodToAdd);
var updateObj = {favoriteFoods: foodArray};
console.log(updateObj)
Person.update({_id: personId}, updateObj, function(err, raw) {
if (err) {
console.log("There was an error");
}
console.log("Updated successfully");
console.log("foodArray inside update function:", foodArray);
});
});
};
This is the whole code on Glitch: https://glitch.com/edit/#!/holly-maroon-pony?path=myApp.js%3A226%3A0
This is the console log for a POST request:
POST
foodArray inside findById: ["spaghetti"]
{ favoriteFoods: ["spaghetti","hamburger"] }
(node:8943) DeprecationWarning: collection.update is deprecated. Use updateOne, updateMany, or bulkWrite instead.
Updated successfully
foodArray inside update function: ["spaghetti","hamburger"]

Answer 1

You can use async and await while making these updates.
var findEditThenSave = async function(personId, done){
var foodToAdd = 'hamburger';
var foodArray = [];
var updateObj;
try{
var data=await Person.findById(personId);
done(null, data);
foodArray = data.favoriteFoods;
console.log("foodArray inside findById: ", foodArray);
foodArray.push(foodToAdd);
updateObj = {favoriteFoods: foodArray};
console.log(updateObj)
}catch(err){
console.log(err);
}
try{
await Person.update({_id: personId}, updateObj);
console.log("Updated successfully");
console.log("foodArray inside update function:", foodArray);
}catch(err){
console.log(err);
}
};

Answer 2

As you can see in your console:
(node:8943) DeprecationWarning: collection.update is
deprecated. Use updateOne, updateMany, or bulkWrite instead.
Updated successfully
So you can get through this using Person.updateOne instead of Person.update
Hope it helps

Answer 3

If you are just planning to update a document and return the updated document you can do something like this
function update(personId) {
var foodToAdd = "hamburger";
const person = Person.findByIdAndUpdate(
personId,
{ $push: { favoriteFoods: foodToAdd } },
{ new: true },
function (err, result) {
if (err) console.log(err);
else console.log(result);
}
);
};