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Querying on an array of objects for specific nested documents with MongoDB?
To query on an array of objects for nested documents, use find(). Let us create a collection with documents −
> db.demo763.insertOne(
... {
... _id:1,
... CountryName:"US",
... "studentInformation": [
... {
... StudentName:"Chris",
... },
... {
... StudentName:"David",
... StudentAge:22
... }
... ]
... }
... );
{ "acknowledged" : true, "insertedId" : 1 }
Display all documents from a collection with the help of find() method −
> db.demo763.find();
This will produce the following output −
{ "_id" : 1, "CountryName" : "US", "studentInformation" : [ { "StudentName" : "Chris" }, { "StudentName" : "David", "StudentAge" : 22 } ] }
Following is how to query an array of objects to fetch specific nested documents −
> db.demo763.find({},
... {
... studentInformation: {
... $elemMatch: {
... StudentAge: {
... $exists: true
... }
... }
... }
... })
This will produce the following output −
{ "_id" : 1, "studentInformation" : [ { "StudentName" : "David", "StudentAge" : 22 } ] }
Updated on: 2020-07-01T06:58:37+05:30
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