Update only a single document in MongoDB

To update only a single document in MongoDB, use the updateOne() method. This method updates the first document that matches the query criteria, even if multiple documents match the filter condition.

Syntax

db.collection.updateOne(
    { filter },
    { $set: { field: "newValue" } }
);

Sample Data

Let us first create a collection with documents ?

db.updateOneDemo.insertMany([
    {"StudentId": 1, "StudentFirstName": "Chris"},
    {"StudentId": 2, "StudentFirstName": "David"},
    {"StudentId": 1, "StudentFirstName": "Mike"}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e06ed3725ddae1f53b621e8"),
        ObjectId("5e06ed3825ddae1f53b621e9"),
        ObjectId("5e06ed3825ddae1f53b621ea")
    ]
}

Display all documents from the collection ?

db.updateOneDemo.find();

{ "_id": ObjectId("5e06ed3725ddae1f53b621e8"), "StudentId": 1, "StudentFirstName": "Chris" }
{ "_id": ObjectId("5e06ed3825ddae1f53b621e9"), "StudentId": 2, "StudentFirstName": "David" }
{ "_id": ObjectId("5e06ed3825ddae1f53b621ea"), "StudentId": 1, "StudentFirstName": "Mike" }

Example: Update Single Document

Update only the first document that matches the criteria ?

db.updateOneDemo.updateOne(
    {},
    { $set: { "StudentFirstName": "Robert" } }
);

{ "acknowledged": true, "matchedCount": 1, "modifiedCount": 1 }

Verify Result

Display all documents to see the update ?

db.updateOneDemo.find();

{ "_id": ObjectId("5e06ed3725ddae1f53b621e8"), "StudentId": 1, "StudentFirstName": "Robert" }
{ "_id": ObjectId("5e06ed3825ddae1f53b621e9"), "StudentId": 2, "StudentFirstName": "David" }
{ "_id": ObjectId("5e06ed3825ddae1f53b621ea"), "StudentId": 1, "StudentFirstName": "Mike" }

Key Points

• updateOne() updates only the first matching document, even with an empty filter {}.
• Use specific filter criteria to target the exact document you want to update.
• Returns matchedCount and modifiedCount in the acknowledgment.

Conclusion

The updateOne() method ensures only a single document is modified, making it ideal when you need precise control over updates. Always use specific filter criteria to target the intended document.