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Convert a field to an array using update operation in MongoDB
To convert a field to an array, use UPDATE operation inside forEach(). Let us first create a collection with documents −
> db.demo18.insertOne({"StudentName":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5e1387fc55d0fc6657d21f0e") }
Following is the query to display all documents from a collection with the help of find() method −
> db.demo18.find();
This will produce the following output −
{ "_id" : ObjectId("5e1387fc55d0fc6657d21f0e"), "StudentName" : "John" }
Here is the query to convert a field to an array using update operation −
> db.demo18.find().forEach(function(myDocument) { ... db.demo18.update( ... { _id: myDocument._id }, ... { "$set": { "StudentName": [myDocument.StudentName] } } ... ); ... })
Following is the query to display all documents from a collection with the help of find() method −
> db.demo18.find();
This will produce the following output −
{ "_id" : ObjectId("5e1387fc55d0fc6657d21f0e"), "StudentName" : [ "John" ] }
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