Renaming column name in a MongoDB collection?

To rename a field (column) name in a MongoDB collection, use the $rename operator. This operator allows you to change field names across multiple documents in a single operation.

Syntax

db.collectionName.updateMany(
    {}, 
    { $rename: { "oldFieldName": "newFieldName" } }
);

Sample Data

Let us create a collection with sample documents ?

db.renamingColumnNameDemo.insertMany([
    { "StudentName": "Larry", "Age": 23 },
    { "StudentName": "Sam", "Age": 26 },
    { "StudentName": "Robert", "Age": 27 }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5c9ee2c6d628fa4220163b9a"),
        ObjectId("5c9ee2d0d628fa4220163b9b"),
        ObjectId("5c9ee2dbd628fa4220163b9c")
    ]
}

Display all documents to verify the initial structure ?

db.renamingColumnNameDemo.find();

{
    "_id": ObjectId("5c9ee2c6d628fa4220163b9a"),
    "StudentName": "Larry",
    "Age": 23
}
{
    "_id": ObjectId("5c9ee2d0d628fa4220163b9b"),
    "StudentName": "Sam",
    "Age": 26
}
{
    "_id": ObjectId("5c9ee2dbd628fa4220163b9c"),
    "StudentName": "Robert",
    "Age": 27
}

Example: Rename Field

Rename the "Age" field to "StudentAge" across all documents ?

db.renamingColumnNameDemo.updateMany(
    {}, 
    { $rename: { "Age": "StudentAge" } }
);

{
    "acknowledged": true,
    "matchedCount": 3,
    "modifiedCount": 3
}

Verify Result

Check that the field has been successfully renamed ?

db.renamingColumnNameDemo.find();

{
    "_id": ObjectId("5c9ee2c6d628fa4220163b9a"),
    "StudentName": "Larry",
    "StudentAge": 23
}
{
    "_id": ObjectId("5c9ee2d0d628fa4220163b9b"),
    "StudentName": "Sam",
    "StudentAge": 26
}
{
    "_id": ObjectId("5c9ee2dbd628fa4220163b9c"),
    "StudentName": "Robert",
    "StudentAge": 27
}

Conclusion

The $rename operator efficiently renames fields across all documents in a collection. Use updateMany() with an empty filter {} to apply the rename operation to all documents simultaneously.