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How to retrieve a nested object in MongoDB?
To retrieve a nested object in MongoDB, use $ operator. Let us first create a collection with documents −
> db.queryNestedObject.insertOne(
... {
... "StudentName" : "James",
... "StudentSubjectScore" : [
... {"StudentMongoDBScore":98},
... {"StudentCScore":92},
... {"StudentJavaScore":91}
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccf49a9dceb9a92e6aa1962")
}Following is the query to display all documents from a collection with the help of find() method −
> db.queryNestedObject.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5ccf49a9dceb9a92e6aa1962"),
"StudentName" : "James",
"StudentSubjectScore" : [
{
"StudentMongoDBScore" : 98
},
{
"StudentCScore" : 92
},
{
"StudentJavaScore" : 91
}
]
}Following is the query to retrieve a nested object −
> db.queryNestedObject.find({'StudentSubjectScore.StudentJavaScore' : 91},{'StudentSubjectScore.$': 1 , _id: 0});This will produce the following output −
{ "StudentSubjectScore" : [ { "StudentJavaScore" : 91 } ] }
Updated on: 30-Jul-2019
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