Filter by several array elements in MongoDB?

To filter documents by several array elements in MongoDB, use the $elemMatch operator. This operator matches documents containing an array field with at least one element that satisfies all specified query criteria.

Syntax

db.collection.find({
    arrayField: {
        $elemMatch: {
            field1: "value1",
            field2: "value2"
        }
    }
});

Sample Data

Let us create a collection with documents containing nested arrays ?

db.filterBySeveralElementsDemo.insertMany([
    {
        "_id": 100,
        "StudentDetails": [
            {
                "StudentName": "John",
                "StudentCountryName": "US"
            },
            {
                "StudentName": "Carol",
                "StudentCountryName": "UK"
            }
        ]
    },
    {
        "_id": 101,
        "StudentDetails": [
            {
                "StudentName": "Sam",
                "StudentCountryName": "AUS"
            },
            {
                "StudentName": "Chris",
                "StudentCountryName": "US"
            }
        ]
    }
]);

{ "acknowledged": true, "insertedIds": [100, 101] }

Display all documents to verify the data ?

db.filterBySeveralElementsDemo.find().pretty();

{
    "_id": 100,
    "StudentDetails": [
        {
            "StudentName": "John",
            "StudentCountryName": "US"
        },
        {
            "StudentName": "Carol",
            "StudentCountryName": "UK"
        }
    ]
}
{
    "_id": 101,
    "StudentDetails": [
        {
            "StudentName": "Sam",
            "StudentCountryName": "AUS"
        },
        {
            "StudentName": "Chris",
            "StudentCountryName": "US"
        }
    ]
}

Example: Filter by Multiple Array Element Fields

Find documents where StudentDetails array contains an element with both StudentName "Sam" AND StudentCountryName "AUS" ?

db.filterBySeveralElementsDemo.find({
    StudentDetails: {
        $elemMatch: {
            StudentName: "Sam",
            StudentCountryName: "AUS"
        }
    }
}).pretty();

{
    "_id": 101,
    "StudentDetails": [
        {
            "StudentName": "Sam",
            "StudentCountryName": "AUS"
        },
        {
            "StudentName": "Chris",
            "StudentCountryName": "US"
        }
    ]
}

Key Points

• $elemMatch ensures all conditions match within the same array element
• Returns the entire document when a match is found, not just the matching array element
• Use when you need to match multiple fields within a single array object

Conclusion

The $elemMatch operator provides precise filtering for complex array structures by ensuring all specified conditions match within the same array element, making it essential for querying documents with nested object arrays.