Get sorted array by specific key in MongoDB

Question

Hello everybody I have a document is structured like that:

{
    name : abc
    message:
    [{
         id: 4,
         status : 0,
         content : "abc"
     },
     {
         id: 2,
         status : 1,
         content : "abc"
     },
     {
         id: 1,
         status : 1,
         content : "abc"
     }
    ]
}

How Can I get the sorted message array by id key and status = 1 I mean

{
     id: 1,
     status : 1,
     content : "abc"
 },
 {
     id: 2,
     status : 1,
     content : "abc"
 },

Thank so much!

ann · Accepted Answer · 2013-03-11 07:14:40Z

1

This solutin in mongo shell, should work out for you. But the aggregate framework is supported from Mongo 2.1 onwards. http://docs.mongodb.org/manual/applications/aggregation/

    db.yourcollection.aggregate([{$unwind:"$message"},{$match:{"message.status":1}},{$project:{_id:0,message:1}},{$sort:{"message.id":1}}])

Since your message key is an array you have to first use the $unwind operator and then use the $match operator.

By default mongo will display the _id of the document. So if you do not want to display the _id, after matching the relevant ones, you could use the $project operator

If you don't want the name key to be displayed, simply don't specify the name key in the project part of the query. By default mongo will only display the keys whose value is 1. If the key is not mentioned it will not display it.

And then you use $sort operator, 1 for asecnding and -1 for descending.

answered Mar 11, 2013 at 7:14

ann

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1 Comment

ann Over a year ago

@tunghk_54 if the answer worked for you, you could mark it right! :)

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