Update two separate arrays in a document with one update call in MongoDB?

To update two separate arrays in a MongoDB document with a single update call, use the $push operator with multiple field specifications in the update document. This allows you to add values to multiple arrays simultaneously.

Syntax

db.collection.update(
    { "query": "condition" },
    { 
        $push: { 
            "arrayField1": "value1",
            "arrayField2": "value2" 
        } 
    }
);

Sample Data

db.twoSeparateArraysDemo.insertMany([
    {
        "StudentName": "Larry",
        "StudentFirstGameScore": [98],
        "StudentSecondGameScore": [77]
    },
    {
        "StudentName": "Mike", 
        "StudentFirstGameScore": [58],
        "StudentSecondGameScore": [78]
    },
    {
        "StudentName": "David",
        "StudentFirstGameScore": [65],
        "StudentSecondGameScore": [67]
    }
]);

Display all documents ?

db.twoSeparateArraysDemo.find();

{
    "_id": ObjectId("5c9b152815e86fd1496b38b8"),
    "StudentName": "Larry",
    "StudentFirstGameScore": [98],
    "StudentSecondGameScore": [77]
}
{
    "_id": ObjectId("5c9b152d15e86fd1496b38b9"),
    "StudentName": "Mike",
    "StudentFirstGameScore": [58],
    "StudentSecondGameScore": [78]
}
{
    "_id": ObjectId("5c9b153315e86fd1496b38ba"),
    "StudentName": "David", 
    "StudentFirstGameScore": [65],
    "StudentSecondGameScore": [67]
}

Update Two Arrays Simultaneously

Push values to both game score arrays for Mike's document in a single update call ?

db.twoSeparateArraysDemo.update(
    { "_id": ObjectId("5c9b152d15e86fd1496b38b9") },
    { 
        $push: {
            "StudentFirstGameScore": 45,
            "StudentSecondGameScore": 99
        }
    }
);

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

Verify Results

Check the updated document to confirm both arrays were modified ?

db.twoSeparateArraysDemo.find({ "StudentName": "Mike" });

{
    "_id": ObjectId("5c9b152d15e86fd1496b38b9"),
    "StudentName": "Mike",
    "StudentFirstGameScore": [58, 45],
    "StudentSecondGameScore": [78, 99]
}

Key Points

• The $push operator can target multiple arrays in a single update operation.
• Each field-value pair in the $push object corresponds to one array field being updated.
• This approach is more efficient than performing separate update calls for each array.

Conclusion

Use $push with multiple field specifications to update two or more arrays simultaneously in MongoDB. This single operation approach improves performance and maintains data consistency across multiple array modifications.