筛选集合，但按内部属性排序

Considering that I have a collection of documents like below and I want to get information returned as follows:

Select all the entries from a campaign with campaignID = 12, sort by entries.questionscorrect in descending order with a limit of 10.

I have made a stab at a number of queries but I seem to be getting stuck on the fact that I am selecting on one level but want to order on a lower level i.e. property.

Here's what I have so far:

db.getCollection('main').find({"id":4}, {"entries": 1}).sort({"questionscorrect": -1}).limit(2)

How can I write this in either Go (Mgo) syntax or straight MongoDB query please?

I keep getting returned information but sorted on the number of

{
    "_id": ObjectId("57f4a590a4be269aa54a0505"),
    "campaignID": 12,
    "name": "name-here",
    "description": "description-here",
    "entries": [{
        "id": 1,
        "nickname": "conorh",
        "name": "conor h***",
        "email": "ch@gmail.com",
        "agreeTerms": true,
        "optInMarketing": false,
        "questionscnswered": 10,
        "questionscorrect": 3
    }, {
        "id": 2,
        "nickname": "bobs",
        "name": "bob smyth",
        "email": "bs12121@gmail.com",
        "agreeTerms": true,
        "optInMarketing": false,
        "questionscnswered": 10,
        "questionscorrect": 6
    }, {
        "id": 3,
        "nickname": "jd12",
        "name": "jane doe",
        "email": "janedough@gmail.com",
        "agreeTerms": true,
        "optInMarketing": false,
        "questionscnswered": 10,
        "questionscorrect": 1
    }]
}

Try below:

db.getCollection('main').aggregate([
{$match: {"campaignID" : 12.0}},
{$unwind:"$entries"},
{$sort: {"entries.questionscorrect": -1}},
{$group:{_id:"$_id", 
    "entries":{$push:"$entries"}}}
])