How do I remove a string from an array in a MongoDB document?

To remove a string from an array in MongoDB, use the $pull operator. This operator removes all instances of a value or values that match a specified condition from an existing array.

Syntax

db.collection.update(
    { <query> },
    { $pull: { <field>: <value> } }
);

Create Sample Data

Let us first create a collection with documents ?

db.removeAStringDemo.insertOne({
    "Score": [45, 67, 89, "John", 98, 99, 67]
});

{
    "acknowledged": true,
    "insertedId": ObjectId("5cda5224b50a6c6dd317adbd")
}

Display all documents from the collection ?

db.removeAStringDemo.find().pretty();

{
    "_id": ObjectId("5cda5224b50a6c6dd317adbd"),
    "Score": [
        45,
        67,
        89,
        "John",
        98,
        99,
        67
    ]
}

Example: Remove String from Array

Remove the string "John" from the Score array ?

db.removeAStringDemo.update(
    { _id: ObjectId("5cda5224b50a6c6dd317adbd") },
    { $pull: { "Score": "John" } }
);

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

Verify Result

Check the document to confirm the string has been removed ?

db.removeAStringDemo.find().pretty();

{
    "_id": ObjectId("5cda5224b50a6c6dd317adbd"),
    "Score": [
        45,
        67,
        89,
        98,
        99,
        67
    ]
}

Conclusion

The $pull operator effectively removes all matching string values from an array. It modifies the existing document by removing the specified value while preserving the array structure and other elements.