Spring Mongo - An aggregation to order by objects in an array - spring

Question

I have the following data:
{
"_id": ObjectID("5e2fa881c3a1a70006c5743c"),
"name": "Some name",
"policies": [
{
"cId": "dasefa-2738-4cf0-90e0d568",
"weight": 12
},
{
"cId": "c640ad67dasd0-92f981583568",
"weight": 50
}
]
}
I'm able to query this with Spring Mongo fine, however I want to be able to order the policies by weight
At the moment I get my results fine with:
return mongoTemplate.find(query, CArea::class.java)
However say I make the following aggregations:
val unwind = Aggregation.unwind("policies")
val sort = Aggregation.sort(Sort.Direction.DESC,"policies.weight")
How can I go and actually apply those to the returned results above? I was hoping that the dot annotation would do the job in my query however didnt do anything e.g. Query().with(Sort.by(options.sortDirection, "policies.weight"))
Any help appreciated.
Thanks.

Answer 1

I am not familier with Spring Mongo, but I guess you can convert the following aggregation to spring code.
db.collection.aggregate([
{
$unwind: "$policies"
},
{
$sort: {
"policies.weight": -1
}
},
{
$group: {
_id: "$_id",
"policies": {
"$push": "$policies"
},
parentFields: {
$first: "$$ROOT"
}
}
},
{
$replaceRoot: {
newRoot: {
$mergeObjects: [
"$parentFields",
{
policies: "$policies"
}
]
}
}
}
])
This will result:
[
{
"_id": "5e2fa881c3a1a70006c5743c",
"name": "Some name",
"policies": [
{
"cId": "c640ad67dasd0-92f981583568",
"weight": 50
},
{
"cId": "dasefa-2738-4cf0-90e0d568",
"weight": 12
}
]
}
]
Playground