How to pull an array element (which is a document) in MongoDB?

To pull (remove) an array element that is a document in MongoDB, use the $pull operator with specific field conditions to match and remove the target document from the array.

Syntax

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

Sample Data

db.pullAnArrayElementDemo.insertOne({
    "StudentDetails": [
        {
            "StudentFirstName": "Chris",
            "StudentScore": 56
        },
        {
            "StudentFirstName": "Robert",
            "StudentScore": 59
        }
    ]
});

{
    "acknowledged": true,
    "insertedId": ObjectId("5cd3b55bedc6604c74817cd5")
}

Example: Remove Document by Field Match

Let's view the initial data ?

db.pullAnArrayElementDemo.find().pretty();

{
    "_id": ObjectId("5cd3b55bedc6604c74817cd5"),
    "StudentDetails": [
        {
            "StudentFirstName": "Chris",
            "StudentScore": 56
        },
        {
            "StudentFirstName": "Robert",
            "StudentScore": 59
        }
    ]
}

Now remove the document where StudentFirstName is "Chris" ?

db.pullAnArrayElementDemo.update(
    {},
    { $pull: { "StudentDetails": { "StudentFirstName": "Chris" } } }
);

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

Verify Result

db.pullAnArrayElementDemo.find().pretty();

{
    "_id": ObjectId("5cd3b55bedc6604c74817cd5"),
    "StudentDetails": [
        {
            "StudentFirstName": "Robert",
            "StudentScore": 59
        }
    ]
}

Conclusion

The $pull operator removes all array elements that match the specified condition. It's ideal for removing document objects from arrays based on field values, providing precise control over array modifications.