Combine update and query parts to form the upserted document in MongoDB?

To combine update and query parts to form an upserted document in MongoDB, use the $set operator with upsert: true. This creates a new document if no match is found, or updates an existing one.

Syntax

db.collection.update(
    { queryCondition },
    { $set: { field: "newValue" } },
    { upsert: true }
);

Sample Data

db.updateWithUpsertDemo.insertMany([
    { "StudentFirstName": "John", "StudentAge": 21 },
    { "StudentFirstName": "Larry", "StudentAge": 23 },
    { "StudentFirstName": "David", "StudentAge": 24 }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cd2a61c345990cee87fd890"),
        ObjectId("5cd2a624345990cee87fd891"),
        ObjectId("5cd2a62c345990cee87fd892")
    ]
}

Example 1: Update Existing Document

Update Larry's name to "Chris" using upsert ?

db.updateWithUpsertDemo.update(
    { _id: ObjectId("5cd2a624345990cee87fd891") },
    { "$set": { "StudentFirstName": "Chris" } },
    { upsert: true }
);

WriteResult({ "nMatched": 1, "nUpserted": 0, "nModified": 1 })

Example 2: Insert New Document with Upsert

Add a new student "Mike" with age 22 if not exists ?

db.updateWithUpsertDemo.update(
    { "StudentFirstName": "Mike" },
    { "$set": { "StudentFirstName": "Mike", "StudentAge": 22 } },
    { upsert: true }
);

WriteResult({ "nMatched": 0, "nUpserted": 1, "nModified": 0 })

Verify Results

db.updateWithUpsertDemo.find().pretty();

{
    "_id": ObjectId("5cd2a61c345990cee87fd890"),
    "StudentFirstName": "John",
    "StudentAge": 21
}
{
    "_id": ObjectId("5cd2a624345990cee87fd891"),
    "StudentFirstName": "Chris",
    "StudentAge": 23
}
{
    "_id": ObjectId("5cd2a62c345990cee87fd892"),
    "StudentFirstName": "David",
    "StudentAge": 24
}
{
    "_id": ObjectId("5cd2a635345990cee87fd893"),
    "StudentFirstName": "Mike",
    "StudentAge": 22
}

Key Points

• upsert: true creates a new document if the query condition finds no match.
• $set ensures only specified fields are updated or inserted.
• The query condition becomes part of the new document structure during upsert.

Conclusion

Using $set with upsert: true provides flexible document management by updating existing records or creating new ones based on the query condition. This approach combines both query and update operations seamlessly.