Get array items inside a MongoDB document?

To get array items in a MongoDB document, use the dot (.) notation to access fields within array elements. This allows you to query documents based on values inside arrays and retrieve specific array items.

Syntax

db.collection.find({"arrayName.fieldName": "value"});

Sample Data

db.demo29.insertMany([
    {
        "StudentDetails": [
            {"StudentName": "Chris", "StudentMarks": 58},
            {"StudentName": "Bob", "StudentMarks": 69}
        ]
    },
    {
        "StudentDetails": [
            {"StudentName": "David", "StudentMarks": 97},
            {"StudentName": "Carol", "StudentMarks": 96}
        ]
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e15fcc08f2315c2efc48e6e"),
        ObjectId("5e15fcd38f2315c2efc48e6f")
    ]
}

Display All Documents

db.demo29.find().pretty();

{
    "_id": ObjectId("5e15fcc08f2315c2efc48e6e"),
    "StudentDetails": [
        {
            "StudentName": "Chris",
            "StudentMarks": 58
        },
        {
            "StudentName": "Bob",
            "StudentMarks": 69
        }
    ]
}
{
    "_id": ObjectId("5e15fcd38f2315c2efc48e6f"),
    "StudentDetails": [
        {
            "StudentName": "David",
            "StudentMarks": 97
        },
        {
            "StudentName": "Carol",
            "StudentMarks": 96
        }
    ]
}

Query Array Items

Find documents containing a student named "David" ?

db.demo29.find({"StudentDetails.StudentName": "David"});

{
    "_id": ObjectId("5e15fcd38f2315c2efc48e6f"),
    "StudentDetails": [
        {
            "StudentName": "David",
            "StudentMarks": 97
        },
        {
            "StudentName": "Carol",
            "StudentMarks": 96
        }
    ]
}

Conclusion

Use dot notation to query array fields in MongoDB documents. The syntax arrayName.fieldName matches documents where any array element contains the specified field value.