MongoDB query to update nested document

To update a nested document in MongoDB, use the $ positional operator with the $set operator. The $ operator identifies the array element that matches the query condition and allows you to update specific fields within that element.

Syntax

db.collection.update(
    {"arrayName.field": "matchValue"},
    { $set: { "arrayName.$.field": "newValue" } }
);

Create Sample Data

Let us create a collection with documents ?

db.demo595.insertOne({
    "Information": [
        { "_id": new ObjectId(), "Name": "Chris" },
        { "_id": new ObjectId(), "Name": "Robert" }
    ]
});

{
    "acknowledged": true,
    "insertedId": ObjectId("5e93369cfd2d90c177b5bce4")
}

Display Current Documents

Display all documents from a collection with the help of find() method ?

db.demo595.find().pretty();

{
    "_id": ObjectId("5e93369cfd2d90c177b5bce4"),
    "Information": [
        {
            "_id": ObjectId("5e93369cfd2d90c177b5bce2"),
            "Name": "Chris"
        },
        {
            "_id": ObjectId("5e93369cfd2d90c177b5bce3"),
            "Name": "Robert"
        }
    ]
}

Update Nested Document

Following is the query to update nested document ?

db.demo595.update(
    {"Information._id": ObjectId("5e93369cfd2d90c177b5bce2")},
    { $set: {"Information.$.Name": "David Miller"} }
);

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

Verify Result

Display all documents to verify the update ?

db.demo595.find().pretty();

{
    "_id": ObjectId("5e93369cfd2d90c177b5bce4"),
    "Information": [
        {
            "_id": ObjectId("5e93369cfd2d90c177b5bce2"),
            "Name": "David Miller"
        },
        {
            "_id": ObjectId("5e93369cfd2d90c177b5bce3"),
            "Name": "Robert"
        }
    ]
}

Conclusion

Use the $ positional operator with $set to update specific fields within nested array documents. The $ identifies the first array element matching your query condition, allowing precise updates to nested data structures.