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How to add a new field to all the documents in a MongoDB collection
To add a new field, use $addFields in MongoDB. Let us create a collection with documents −
> db.demo712.insertOne({"Name":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5ea85f675d33e20ed1097b82") } > db.demo712.insertOne({"Name":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5ea85f6a5d33e20ed1097b83") } > db.demo712.insertOne({"Name":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5ea85f6e5d33e20ed1097b84") }
Display all documents from a collection with the help of find() method −
> db.demo712.find();
This will produce the following output −
{ "_id" : ObjectId("5ea85f675d33e20ed1097b82"), "Name" : "John" } { "_id" : ObjectId("5ea85f6a5d33e20ed1097b83"), "Name" : "Chris" } { "_id" : ObjectId("5ea85f6e5d33e20ed1097b84"), "Name" : "Bob" }
Following is the query to add a new field −
> db.demo712.aggregate([ ... { ... $addFields: ... { ... "TeacherName":"Robert" ... } ... } ... ] ... );
This will produce the following output −
{ "_id" : ObjectId("5ea85f675d33e20ed1097b82"), "Name" : "John", "TeacherName" : "Robert" } { "_id" : ObjectId("5ea85f6a5d33e20ed1097b83"), "Name" : "Chris", "TeacherName" : "Robert" } { "_id" : ObjectId("5ea85f6e5d33e20ed1097b84"), "Name" : "Bob", "TeacherName" : "Robert" }
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