Mongo Sort Documents by value in array - arrays

Question

I have a list of Students. Each one has an array of points they've earned by category in an array named lightTrail. I want the top 5 people with the most behavior points which is shown at index 1 in the lightTrail array. If it is a tie the second sort field is their total points which is shown at index 0.
Here is what I tried:
db.students.aggregate([{
$project: {
fname: 1,
surname: 1,
lightTrails: 1,
'_id': 0
}
},
{
$sort: {
"lightTrails.1": -1,
"lightTrails.0": -1
}
}, {
$limit: 5
}
], {
allowDiskUse: true
})
This is the result I wanted:
{
"fname": "Jim",
surname: "Jones",
lightTrails: [200, 70, 30, 30, 15, 15, 40]
}, {
"fname": "Sean",
surname: "Marx",
lightTrails: [180, 50, 50, 20, 20, 15, 25]
}, {
"fname": "Todd",
surname: "Lull",
lightTrails: [150, 40, 60, 15, 15, 10, 10]
}, {
"fname": "Flynn",
surname: "Moore",
lightTrails: [100, 40, 25, 15, 5, 10, 5]
}, {
"fname": "Al",
surname: "Ryan",
lightTrails: [80, 20, 20, 10, 10, 10, 10]
}
The result I got was just 5 students no order:
{
"fname": "Flynn",
surname: "Moore",
lightTrails: [100, 40, 25, 15, 5, 10, 5]
}, {
"fname": "Jim",
surname: "Jones",
lightTrails: [200, 70, 30, 30, 15, 15, 40]
}, {
"fname": "Al",
surname: "Ryan",
lightTrails: [80, 20, 20, 10, 10, 10, 10]
}, {
"fname": "Todd",
surname: "Lull",
lightTrails: [150, 40, 60, 15, 15, 10, 10]
}, {
"fname": "Sean",
surname: "Marx",
lightTrails: [180, 50, 50, 20, 20, 15, 25]
}
I found 2 similar questions but one was for an array of documents which didn't work for me and the other wasn't really asking the same question at all.

Answer 1

You can achieve this by find query. No need to use aggregation.
Query:
db.students.find({},{fname:1,surname:1,lightTrails:1,_id:0}).sort({"lightTrails.0":-1,"lightTrails.1":-1}).limit(5)
Result:
{ "fname" : "Jim", "surname" : "Jones", "lightTrails" : [ 200, 70, 30, 30, 15, 15, 40 ] }
{ "fname" : "Sean", "surname" : "Marx", "lightTrails" : [ 180, 50, 50, 20, 20, 15, 25 ] }
{ "fname" : "Todd", "surname" : "Lull", "lightTrails" : [ 150, 40, 60, 15, 15, 10, 10 ] }
{ "fname" : "Flynn", "surname" : "Moore", "lightTrails" : [ 100, 40, 25, 15, 5, 10, 5 ] }
{ "fname" : "Al", "surname" : "Ryan", "lightTrails" : [ 80, 20, 20, 10, 10, 10, 10 ] }