How to update the _id of a MongoDB Document?

You cannot update it but you can save a new id and remove the old id. Follow some steps in order to update the _id of a MongoDB. The steps are as follows:

Step1: In the first step, you need to store ObjectId into a variable.

anyVariableName=db.yourCollectionName.findOne({_id:yourObjectIdValue)});

Step 2: In the second step, you need to set a new id.

yourDeclaredVariableName._id=yourNewObjectIdValue;

Step 3: In the third step, you need to insert new id on a document.

db.yourCollectionName.insert(yourDeclaredVariableName);

Step 4: In the fourth step, you need to remove the old id.

db.yourCollectionName.remove({_id:yourOldObjectIdValue)});

To understand the above steps, let us create a collection with document. The query to create a collection with document is as follows:

> db.updateIdDemo.insertOne({"StudentName":"Robert"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c6ebfec6fd07954a4890683")
}
> db.updateIdDemo.insertOne({"StudentName":"Chris"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c6ebff66fd07954a4890684")
}
> db.updateIdDemo.insertOne({"StudentName":"Maxwell"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c6ebfff6fd07954a4890685")
}

Display all documents from a collection with the help of find() method. The query is as follows:

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

The following is the output:

{ "_id" : ObjectId("5c6ebfec6fd07954a4890683"), "StudentName" : "Robert" }
{ "_id" : ObjectId("5c6ebff66fd07954a4890684"), "StudentName" : "Chris" }
{ "_id" : ObjectId("5c6ebfff6fd07954a4890685"), "StudentName" : "Maxwell" }

The following is the query to update the _id of a MongoDB document:

Step1:
> myId=db.updateIdDemo.findOne({_id:ObjectId("5c6ebfec6fd07954a4890683")});
{ "_id" : ObjectId("5c6ebfec6fd07954a4890683"), "StudentName" : "Robert" }

Step 2:
> myId._id=ObjectId("5c6ebfec6fd07954a4890689");
ObjectId("5c6ebfec6fd07954a4890689")

Step 3:
> db.updateIdDemo.insert(myId);
WriteResult({ "nInserted" : 1 })

Step 4:
> db.updateIdDemo.remove({_id:ObjectId("5c6ebfec6fd07954a4890683")});
WriteResult({ "nRemoved" : 1 })

Let us check the _id has been updated or not. Display all documents from a collection with the help of find() method:

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

The following is the output:

{ "_id" : ObjectId("5c6ebff66fd07954a4890684"), "StudentName" : "Chris" }
{ "_id" : ObjectId("5c6ebfff6fd07954a4890685"), "StudentName" : "Maxwell" }
{ "_id" : ObjectId("5c6ebfec6fd07954a4890689"), "StudentName" : "Robert" }

Look at the sample output, the _id of “StudentName”:”Robert” has been changed.