'sorting in mongodb aggregation according to timestamp

i have this collection

{ "ip" : "192.168.141.1", "ifsIndex" : "28", "link" : "1", "timeStamp" : "19-01-2018 18:12:42" } { "ip" : "192.168.141.1", "ifsIndex" : "30", "link" : "1", "timeStamp" : "19-01-2018 18:12:42" } { "ip" : "192.168.141.1", "ifsIndex" : "32", "link" : "1", "timeStamp" : "19-01-2018 18:12:42" } { "ip" : "192.168.141.1", "ifsIndex" : "29", "link" : "1", "timeStamp" : "19-01-2018 18:12:42" } { "ip" : "192.168.141.1", "ifsIndex" : "31", "link" : "1", "timeStamp" : "19-01-2018 18:12:42" } { "ip" : "192.168.141.1", "ifsIndex" : "28", "link" : "1", "timeStamp" : "19-01-2018 18:14:16" } { "ip" : "192.168.141.1", "ifsIndex" : "29", "link" : "1", "timeStamp" : "19-01-2018 18:16:33" } { "ip" : "192.168.141.1", "ifsIndex" : "32", "link" : "1", "timeStamp" : "19-01-2018 18:14:09" } { "ip" : "192.168.141.1", "ifsIndex" : "28", "link" : "1", "timeStamp" : "19-01-2018 18:16:33" } { "ip" : "192.168.141.1", "ifsIndex" : "30", "link" : "1", "timeStamp" : "19-01-2018 18:14:16" } { "ip" : "192.168.141.1", "ifsIndex" : "31", "link" : "1", "timeStamp" : "19-01-2018 18:16:33" } { "ip" : "192.168.141.1", "ifsIndex" : "29", "link" : "1", "timeStamp" : "19-01-2018 18:14:16" } { "ip" : "192.168.141.1", "ifsIndex" : "30", "link" : "1", "timeStamp" : "19-01-2018 18:16:33" } { "ip" : "192.168.141.1", "ifsIndex" : "31", "link" : "1", "timeStamp" : "19-01-2018 18:14:16" } { "ip" : "192.168.141.1", "ifsIndex" : "32", "link" : "1", "timeStamp" : "19-01-2018 18:16:33" }

i want to group ip address and ifsIndex together and show the array of link and timeStamp and show the result in sorted timestamp.i tried this

db.events.aggregate([{$group:{_id:{"ifIndex":"$ifsIndex","ip":"$ip"},status:{$push:"$link"},timeStamp:{$push:"$timeStamp"}}},{$sort:{"timeStamp":1}}])

result i get is not i want. some values are not sorted in timeStamp

{ "_id" : { "ifIndex" : "31", "ip" : "192.168.141.1" }, "status" : [ "1", "1", "1" ], "timeStamp" : [ "19-01-2018 18:12:42", "19-01-2018 18:16:33", "19-01-2018 18:14:16" ] }
{ "_id" : { "ifIndex" : "29", "ip" : "192.168.141.1" }, "status" : [ "1", "1", "1" ], "timeStamp" : [ "19-01-2018 18:12:42", "19-01-2018 18:16:33", "19-01-2018 18:14:16" ] }
{ "_id" : { "ifIndex" : "32", "ip" : "192.168.141.1" }, "status" : [ "1", "1", "1" ], "timeStamp" : [ "19-01-2018 18:12:42", "19-01-2018 18:14:09", "19-01-2018 18:16:33" ] }
{ "_id" : { "ifIndex" : "30", "ip" : "192.168.141.1" }, "status" : [ "1", "1", "1" ], "timeStamp" : [ "19-01-2018 18:12:42", "19-01-2018 18:14:16", "19-01-2018 18:16:33" ] }
{ "_id" : { "ifIndex" : "28", "ip" : "192.168.141.1" }, "status" : [ "1", "1", "1" ], "timeStamp" : [ "19-01-2018 18:12:42", "19-01-2018 18:14:16", "19-01-2018 18:16:33" ] }

the timeStamp of ifIndex 31 and 29 are not sorted and others are sorted. what i am doing wrong here ?

arraysmongodbsortingaggregation-framework


Solution 1:[1]

I use this to sort any timestamp field using aggregation, I am sorting it by the latest update time of the document. If you need you can group it later. You can learn more about aggregate $sort here.

aggregate.push({ $sort: { updated_at: -1 } });

What I do is I make blocks of aggregate actions push them into an array and execute it all together. I find it easier to debug if something is not working properly.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 BivorAdrito

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