How can I update child objects in MongoDB?

To update child objects, use $set operator. Let us first create a collection with document −

>db.updateChildObjectsDemo.insertOne({"StudentName":"Chris","StudentOtherDetails":{"StudentSubject":"MongoDB","StudentCountryName":"AUS"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ce964e078f00858fb12e91f") }

Following is the query to display all documents from a collection with the help of find() method −

> db.updateChildObjectsDemo.find().pretty();

This will produce the following output −

{    "_id" : ObjectId("5ce964e078f00858fb12e91f"),    "StudentName" : "Chris",    "StudentOtherDetails" : {       "StudentSubject" : "MongoDB",       "StudentCountryName" : "AUS"    } }

Following is the query to update child objects in MongoDB −

> db.updateChildObjectsDemo.update({"StudentName" : "Chris"},{$set:{"StudentOtherDetails.StudentCountryName":"UK"}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Let us check the document once again −

> db.updateChildObjectsDemo.find().pretty();

This will produce the following output −

{    "_id" : ObjectId("5ce964e078f00858fb12e91f"),    "StudentName" : "Chris",    "StudentOtherDetails" : {       "StudentSubject" : "MongoDB",       "StudentCountryName" : "UK"    } }