Mongo update multiple fields of an object which is inside an array - arrays

Question

Using Mongo findOneAndUpdate, I am trying to update just some fields in an object from array of objects.
My object:
mainObject:{
_id: '123',
array:[
{title:'title' , name:'name', keep:'keep'},
{title:'title', keep:'keep'},
]
}
I want to change title and name for the first object in array, and keep the keep field unchanged.
This is my closest approach using Positional Operator:
// here i set dynamic arguments for query update
// sometimes i need to update only one field, sometime i need to update more fields
// also, is there a better way to do this?
let title
let name
if (args.title) {
title = { title: args.title };
}
if (args.name) {
name= { name: args.name};
}
db.Test.findOneAndUpdate(
{ _id: args.id, 'mainObject.array.title': args.title},
{
$set: {
'mainObject.array.$[]': {
...title,
...name
}
}
}
)
this problem is that it replace the whole object, the result is:
mainObject:{
array:[
{title:'changed' , name:'changed'}, //without keep... :(
{title:'title', keep:'keep'},
]
}
Should I use aggregation framework for this?

Answer 1

It has to be like this :
db.test.findOneAndUpdate({'mainObject.array.title': 'title'},
{$set : {'mainObject.array.$.title':'changed','mainObject.array.$.name': 'changed'}})
From your query, $ will update the first found element in array that matches the filter query, if you've multiple elements/objects in array array then you can use $[] to update all of those, let's see your query :
'mainObject.array.$[]': {
...title,
...name
}
Major issue with above query is that it will update all the objects in array array that match the filter with below object :
{
...title,
...name
}
So, it a kind of replace entire object. Instead use . notation to update particular values.