mongodb sorting array documents - mongodb

Question

This is my document i want to sort array documents by ascending order to get so for that my queries are in following code.but i am not getting the docs in sorted way.
The query is
db.sample.find({_id: ObjectId("55b32f5957e47fabd30c5d2e")}).sort({'naresh.ts':1}).pretty();
This is the result I am getting
{
"_id" : ObjectId("55b32f5957e47fabd30c5d2e"),
"naresh" : [
{
"ts" : "hi",
"created_by" : 1437806425105
},
{
"ts" : "hello",
"created_by" : 1437806425105
},
{
"ts" : "waht",
"created_by" : 1437807757261
},
{
"ts" : "lefo",
"created_by" : 1437807768514
},
{
"ts" : "lefow",
"created_by" : 1437807775719
}
]
}

Answer 1

You can use $aggregation like following query:
db.collection.aggregate({
"$match": {
"_id": ObjectId("55b32f5957e47fabd30c5d2e")
}
}, {
$unwind: "$naresh"
}, {
$sort: {
"naresh.ts": 1
}
}, {
"$group": {
_id: "$_id",
"naresh": {
$push: "$naresh"
}
}
})

Answer 2

The cursor .sort() only looks at the values in the array to decide to use the "smallest" value of the specified field ( in ascending order ) to determine how to "sort" the documents in the response. This does not "sort" the array content itself.
In order to sort the array, you need to use the aggregation framework to manipulate the document:
db.sample.aggregate([
{ "$match": { "_id": ObjectId("55b32f5957e47fabd30c5d2e") },
{ "$unwind": "$naresh" },
{ "$sort": { "$naresh.ts": 1 } },
{ "$group": {
"_id": "$_id",
"naresh": { "$push": "$naresh" }
}}
])
That sorts the array.
Better yet, if you "always" want then results sorted then do it as you update the document:
db.sample.update({},{ "$push": { "$each": [], "$sort": { "ts": 1 } } },{ "multi": true })
And use those same, $each and $sort modifiers when adding new elements to the array and the content will remain sorted.

Answer 3

If you want just query the collection and get the output sorted, then Blackes Seven's answer will work perfectly for you.
However if you want to update the documents in the sorted order, go with this update query:
update(
{
_id: ObjectId("55b32f5957e47fabd30c5d2e")
},
{
$push: {
naresh: {
$each: [],
$sort: {created_by: 1}
}
}
}
)