0The $rename operator helps you change the names of fields in your MongoDB documents easily.
db.collection.updateMany(
{ <filter> },
{ $rename: { "oldFieldName": "newFieldName" } }
)The $rename operator is used inside an update command.
You can rename multiple fields by adding more pairs inside the $rename object.
username to user_name in all documents in the users collection.db.users.updateMany({}, { $rename: { "username": "user_name" } })price to cost and desc to description only for documents where category is "books".db.products.updateMany(
{ "category": "books" },
{ $rename: { "price": "cost", "desc": "description" } }
)This example creates a collection items with two documents. It then renames the field price to cost in all documents. Finally, it shows the updated documents.
use shopDB // Insert sample documents db.items.insertMany([ { _id: 1, name: "Pen", price: 1.5 }, { _id: 2, name: "Notebook", price: 3.0 } ]) // Rename field 'price' to 'cost' db.items.updateMany({}, { $rename: { "price": "cost" } }) // Find all documents to see the change db.items.find().pretty()
If the new field name already exists in a document, $rename will overwrite it.
You cannot rename a field to the same name it already has.
$rename changes field names in MongoDB documents.
It works inside update commands like updateMany.
You can rename one or many fields at once.
$rename operator do in MongoDB?$rename$rename operator is used to change the name of an existing field in MongoDB documents.$unset which deletes fields, or $set which changes values or adds fields, $rename only changes field names.$rename changes field names [OK]oldName to newName in all documents of a collection named users?$rename operator requires a mapping object where both old and new field names are strings, so keys and values must be quoted.'oldName' and 'newName'. Options A, C, and D miss quotes on either key or value, causing syntax errors.products with documents:{ "_id": 1, "name": "Pen", "cost": 5 }db.products.updateOne({ _id: 1 }, { $rename: { "cost": "price" } })db.products.findOne({ _id: 1 })?$rename operator changes the field name from cost to price in the matched document.cost is removed and replaced by price with the same value 5. Other fields remain unchanged.$rename moves field value to new name [OK]db.orders.updateMany({}, { $rename: { "orderDate": "date" } })orders does not exist. is unlikely as the error is specific to $rename. The updateMany command requires a filter other than {}. is invalid because {} is a valid filter for updateMany.employees with documents containing fields fname and lname. You want to rename fname to firstName and lname to lastName in one update command. Which command correctly does this?$rename operator accepts an object mapping old field names to new field names, allowing multiple renames in one command.Pass the test and this pattern moves unknown strong while earning +1 Grip toward your certificate.