find() return the latest value only on MongoDB - mongodb

Question

I have this collection in MongoDB that contains the following entries. I'm using Robo3T to run the query.
{
"_id" : ObjectId("xxx1"),
"Evaluation Date" : "2021-09-09",
"Results" : [
{
"Name" : "ABCD",
"Version" : "3.2.x"
}
]
"_id" : ObjectId("xxx2"),
"Evaluation Date" : "2022-09-09",
"Results" : [
{
"Name" : "ABxD",
"Version" : "5.2.x"
}
]
}
This document contains multiple entries of similar format. Now, I need to extract the latest value for "Version".
Expected output:
5.2.x
Measures I've taken so far:
(1) I've only tried findOne() and while I was able to extract the value of "Version": db.getCollection('TestCollectionName').findOne().Results[0].Version
...only the oldest entry was returned.
3.2.x
(2) Using the find().sort().limit() like below, returns the entire document for the latest entry and not just the data value that I wanted; db.getCollection('TestCollectionName').find({}).sort({"Results.Version":-1}).limit(1)
Results below:
"_id" : ObjectId("xxx2"),
"Evaluation Date" : "2022-09-09",
"Results" : [
{
"Name" : "ABxD",
"Version" : "5.2.x"
}
]
(3) I've tried to use sort() and limit() alongside findOne() but I've read that findOne is maybe deprecated and also not compatible with sort. And thus, resulting to an error.
(4) Finally, if I try to use sort and limit on find like this: db.getCollection('LD_exit_Evaluation_Result_MFC525').find({"Results.New"}).sort({_id:-1}).limit(1) I would get an unexpected token error.
What would be a good measure for this?
Did I simply mistake to/remove a bracket or need to reorder the syntax?
Thanks in advance.

Answer 1

I'm not sure if I understood well, but maybe this could be what are you looking for:
db.collection.aggregate([
{
"$project": {
lastResult: {
"$last": "$Results"
},
},
},
{
"$project": {
version: "$lastResult.Version",
_id: 0
}
}
])
It uses aggregate with some operators: the first $project calculate a new field called lastResult with the last element of each array using $last operator. The second $project is just to clean the output. If you need the _id reference, just remove _id: 0 or change its value to 1.
You can check how it works here: https://mongoplayground.net/p/jwqulFtCh6b
Hope I helped