Sorting an array in spring-data mongodb

Question

I have a collection like :

{"x":{"y":[
{"date":ISODate("2014-07-24T21:00:00.000Z"),"k":5 },
{"date":ISODate("2014-07-22T21:00:00.000Z"),"k":6 } ] }}

I want to sort y array according to "date" parameter.So i made the code like this :

query.with(new Sort(Sort.Direction.ASC, "y.date"));

I want to output like this:

{"x":{"y":[
    {"date":ISODate("2014-07-22T21:00:00.000Z"),"k":5 },
    {"date":ISODate("2014-07-24T21:00:00.000Z"),"k":6 } ] }}

How can i make the output like this ? is the code that i made ,it is ok ?

vmr · Accepted Answer · 2014-08-26 11:41:01Z

2

Using aggregation, your query should look like this, since you want to sort elements of 'y' based on 'date' in ascending order.

db.test.aggregate([ {$unwind: "$y"},
{$sort: {"y.date":1}},
{$group: {_id:"$_id", y: {$push:"$y"}}} ]);

answered Aug 26, 2014 at 11:41

vmr

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2 Comments

thanx @vmr.But "unwind" already split the documents and every document has one y...sorting has no mean in like this situation.

The order will be maintained during grouping per _id, so it should reach your target.