MongoDB- ADD, MODIFY/RENAME, or DELETE Key

By Atul Rai | Last Updated: November 7, 2020 Previous       Next

In MongoDB database, db.collection.update({criteria},{$operator: {new value}}) or db.collection.updateMany({criteria},{$operator: {new value}}) method is used to ADD, DELETE, or MODIFY/RENAME the existing document in the collection.

1. ADD

The $set operator is used to adding a new key/field in the existing document.

Syntax:

{ $set: { <field1>: <value1>, ... } }

1.1. Add a new key in a single document

> db.employee.update({_id: ObjectId("5fa6b5d16230249b7475c770")},{ $set : { country : null} })

1.2. Add a new key in all document

> db.employee.updateMany({},{ $set : { country : null} })

2. MODIFY/RENAME

The $rename operator rename/modify the name of a field/key of the existing document.

Syntax:

{$rename: { <field1>: <newName1>, <field2>: <newName2>, ... } }

2.1. Rename key in a single document

> db.employee.update({_id: ObjectId("5fa6b5d16230249b7475c770")},{$rename: { "name": "fullName"} })

2.2. Rename key in all document

> db.employee.updateMany({},{$rename: { "name": "fullName"} })

3. DELETE

The $unset operator deletes the specified field from the existing document.

Syntax:

{ $unset: { <field1>: "", ... } }

3.1. Delete key from a single document

> db.employee.update({_id: ObjectId("5fa6b5d16230249b7475c770")},{ $unset : { city : 1} })

3.2. Delete key from all document

> db.employee.updateMany({},{ $unset : { city : 1} })

References

1. MongoDB- INSERT, SELECT, UPDATE, and DELETE Query
2. How to set Username, Password, and Roles to MongoDB Database
3. Field Update Operators- MongoDB Manual