Retrieve highest score for each game using aggregate in MongoDB - mongodb

Question

I am working on a database of various games and i want to design a query that returns top scorer from each game with specific player details.
The document structure is as follows:
db.gaming_system.insertMany(
[
{
"_id": "01",
"name": "GTA 5",
"high_scores": [
{
"hs_id": 1,
"name": "Harry",
"score": 6969
},
{
"hs_id": 2,
"name": "Simon",
"score": 8574
},
{
"hs_id": 3,
"name": "Ethan",
"score": 4261
}
]
},
{
"_id": "02",
"name": "Among Us",
"high_scores": [
{
"hs_id": 1,
"name": "Harry",
"score": 926
},
{
"hs_id": 2,
"name": "Simon",
"score": 741
},
{
"hs_id": 3,
"name": "Ethan",
"score": 841
}
]
}
]
)
I have created a query using aggregate which returns the name of game and the highest score for that game as follows
db.gaming_system.aggregate(
{ "$project": { "maximumscore": { "$max": "$high_scores.score" }, name:1 } },
{ "$group": { "_id": "$_id", Name: { $first: "$name" }, "Highest_Score": { "$max": "$maximumscore" } } },
{ "$sort" : { "_id":1 } }
)
The output from my query is as follows:
{ "_id" : "01", "Name" : "GTA 5", "Highest_Score" : 8574 }
{ "_id" : "02", "Name" : "Among Us", "Highest_Score" : 926 }
I want to generate output which also provides the name of player and "hs_id" of that player who has the highest score for each game as follows:
{ "_id" : "01", "Name" : "GTA 5", "Top_Scorer" : "Simon", "hs_id": 2, "Highest_Score" : 8574 }
{ "_id" : "02", "Name" : "Among Us", "Top_Scorer" : "Harry", "hs_id": 1, "Highest_Score" : 926 }
What should be added to my query using aggregate pipeline?

Answer 1

[
{
$unwind: "$high_scores" //unwind the high_scores, so you can then sort
},
{
$sort: {
"high_scores.score": -1 //sort the high_scores, irrelevant of game, because we are going to group in next stage
}
},
{
//now group them by _id, take the name and top scorer from $first (which is the first in that group as sorted by score in descending order
$group: {
_id: "$_id",
name: {
$first: "$name"
},
Top_Scorer: {
$first: "$high_scores"
}
}
}
]