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Sort by subdocument in MongoDB
To sort by subdocument, use $sort in MongoDB. Let us create a collection with documents −
> db.demo245.insertOne( ... { ... "_id": 101, ... "deatils": [ ... { "DueDate": new ISODate("2019-01-10"), "Value": 45}, ... {"DueDate": new ISODate("2019-11-10"), "Value": 34 } ... ] ... } ...); { "acknowledged" : true, "insertedId" : 101 } > db.demo245.insertOne( ... { ... "_id": 102, ... "details": [ ... { "DueDate": new ISODate("2019-12-11"), "Value": 29}, ... {"DueDate": new ISODate("2019-03-10"), "Value": 78} ... ] ... } ...); { "acknowledged" : true, "insertedId" : 102 }
Display all documents from a collection with the help of find() method −
> db.demo245.find();
This will produce the following output −
{ "_id" : 101, "deatils" : [ { "DueDate" : ISODate("2019-01-10T00:00:00Z"), "Value" : 45 }, { "DueDate" : ISODate("2019-11-10T00:00:00Z"), "Value" : 34 } ] } { "_id" : 102, "details" : [ { "DueDate" : ISODate("2019-12-11T00:00:00Z"), "Value" : 29 }, { "DueDate" : ISODate("2019-03-10T00:00:00Z"), "Value" : 78 } \ ] }
Following is the query to sort by subdocument −
> db.demo245.aggregate([ ... { "$unwind": "$details" }, ... { "$sort": { "_id": 1, "details.Value": -1 } }, ... { "$group": { ... "_id": "$_id", ... "details": { "$push": "$details" } ... }}, ... { "$sort": { "details.Value": -1 } } ...])
This will produce the following output −
{ "_id" : 102, "details" : [ { "DueDate" : ISODate("2019-03-10T00:00:00Z"), "Value" : 78 }, { "DueDate" : ISODate("2019-12-11T00:00:00Z"), "Value" : 29 } ] }
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