mongodb sorting children of an array in a document [duplicate]

Question

My data looks like this:

{
    "name":"dan",
    "somestring":"asdf",
    "friends":[

            {
                "name": "carl",
                "height":180,
                ...
            },
            {
                "name": "john",
                "height":165,
                ...
            },
            {
                "name": "jim",
                "height":170,
                ...
            }

    ]
},
...

I would like retrieve the document where the friends are sorted by height descending.

I tried db.getCollection('users').find({"name" : "dan"}, {"friends" : 1}).sort({"friends.height" : -1}) but the friends list stays the same.

EDIT: I messed up the structure of my data, I fixed the array to look like an array...

Answer 1

An option is to run an aggregation that:

1. unwinds the array
2. sorts by friends.name
3. regroups

The pipeline should look something like this:

db.collection.aggregate([
    { $match: { name: 'dan' }},
    { $unwind: '$friends' },
    { $sort: { 'friends.height': -1 }},
    { $group: { _id: '$name', friends: { $push: '$friends'}}])