Adding new property to each document in a large MongoDB collection?

You can use update command along with forEach() for large collection. Let us first create a collection with documents

>db.addingNewPropertyDemo.insertOne({"StudentName":"John","StudentAge":23,"CountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ca1e61866324ffac2a7dc56") } >db.addingNewPropertyDemo.insertOne({"StudentName":"David","StudentAge":21,"CountryName":"AUS"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ca1e62366324ffac2a7dc57") } >db.addingNewPropertyDemo.insertOne({"StudentName":"Bob","StudentAge":21,"CountryName":"UK"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ca1e62d66324ffac2a7dc58") }

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

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

This will produce the following output

{    "_id" : ObjectId("5ca1e61866324ffac2a7dc56"),    "StudentName" : "John",    "StudentAge" : 23,    "CountryName" : "US" } {    "_id" : ObjectId("5ca1e62366324ffac2a7dc57"),    "StudentName" : "David",    "StudentAge" : 21,    "CountryName" : "AUS" } {    "_id" : ObjectId("5ca1e62d66324ffac2a7dc58"),    "StudentName" : "Bob",    "StudentAge" : 21,    "CountryName" : "UK" }

Following is the query to add new property to each document in a large collection

> db.addingNewPropertyDemo.find().forEach(function(data){ db.addingNewPropertyDemo.update({_id: data._id}, {$set: { StudentNameInUpperCase: data.StudentName.toUpperCase() }}) });

Let us check a new property is added or not

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

Following is the output displaying the new property as well

{    "_id" : ObjectId("5ca1e61866324ffac2a7dc56"),    "StudentName" : "John",    "StudentAge" : 23,    "CountryName" : "US",    "StudentNameInUpperCase" : "JOHN" } {    "_id" : ObjectId("5ca1e62366324ffac2a7dc57"),    "StudentName" : "David",    "StudentAge" : 21,    "CountryName" : "AUS",    "StudentNameInUpperCase" : "DAVID" } {    "_id" : ObjectId("5ca1e62d66324ffac2a7dc58"),    "StudentName" : "Bob",    "StudentAge" : 21,    "CountryName" : "UK",    "StudentNameInUpperCase" : "BOB" }

Look at the above sample output, StudentNameInUpperCase property is added.