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How to filter array in subdocument with MongoDB?
You can use aggregate and unwind the array list before applying match. To understand the above concept, let us create a collection with documents. The query to create a collection with document is as follows:
> db.filterArray.insertOne( { "L": [{ "N":1 }, { "N":2 } , { "N":3 }, { "N":4 }, { "N":5 } ]});The following is visible after running the above query:
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6d63f2734e98fc0a434aeb")
}Display document from a collection with the help of find() method. The query is as follows:
> db.filterArray.find().pretty();
The following is the output:
{
"_id" : ObjectId("5c6d63f2734e98fc0a434aeb"),
"L" : [
{
"N" : 1
},
{
"N" : 2
},
{
"N" : 3
},
{
"N" : 4
},
{
"N" : 5
}
]
}Here is the query to filter array in subdocument with MongoDB. We have used $gt to get the fields greater than 3:
> db.filterArray.aggregate({ $match:{_id:ObjectId("5c6d63f2734e98fc0a434aeb")}}, {
$unwind:'$L'}, {$match:{'L.N':{$gt:3}}},
{$group:{_id:'$_id',subDocument:{$push:'$L.N'}}}).pretty();The following is the output:
{
"_id" : ObjectId("5c6d63f2734e98fc0a434aeb"),
"subDocument" : [
4,
5
]
}
Updated on: 30-Jul-2019
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