MongoDB query to update an array using FindAndUpdate()?

To update an array in MongoDB, use the findAndModify() method combined with the $ positional operator to target specific array elements. This method updates the document and returns either the original or updated version.

Syntax

db.collection.findAndModify({
    query: { "arrayField": "matchValue" },
    update: { $set: { "arrayField.$": "newValue" } }
});

Sample Data

db.demo152.insertMany([
    {"id": 102, "Name": ["Chris", "David"], "Score": 45},
    {"id": 103, "Name": ["Mike", "Carol"], "Score": 65}
]);

{
    "acknowledged": true,
    "insertedIds": {
        "0": ObjectId("5e3515bcfdf09dd6d08539dd"),
        "1": ObjectId("5e3515cafdf09dd6d08539de")
    }
}

Display all documents from the collection ?

db.demo152.find();

{ "_id": ObjectId("5e3515bcfdf09dd6d08539dd"), "id": 102, "Name": ["Chris", "David"], "Score": 45 }
{ "_id": ObjectId("5e3515cafdf09dd6d08539de"), "id": 103, "Name": ["Mike", "Carol"], "Score": 65 }

Example: Update Array Element

Update "Chris" to "Robert" in the Name array for document with id 102 ?

var result = db.demo152.findAndModify({
    query: {
        id: 102,
        Score: {$lt: 50},
        Name: "Chris"
    },
    update: {
        $set: {"Name.$": "Robert"},
        $inc: {Score: 20}
    }
});

Verify the update ?

db.demo152.find();

{ "_id": ObjectId("5e3515bcfdf09dd6d08539dd"), "id": 102, "Name": ["Robert", "David"], "Score": 65 }
{ "_id": ObjectId("5e3515cafdf09dd6d08539de"), "id": 103, "Name": ["Mike", "Carol"], "Score": 65 }

Key Points

• The $ positional operator updates the first matching array element
• findAndModify() provides atomic update operations
• Combine multiple update operations using $set and $inc

Conclusion

Use findAndModify() with the $ positional operator to update specific array elements atomically. This method ensures precise targeting of array elements while allowing multiple field updates in a single operation.