Match element in array of MongoDB?

To match elements in arrays in MongoDB, you can use the $or operator to search for documents where any array element matches one or more conditions. This approach is useful when you want to find documents containing arrays with specific field values.

Syntax

db.collection.find({
    $or: [
        {"arrayField.subfield1": "value1"},
        {"arrayField.subfield2": "value2"}
    ]
}).limit(1);

Sample Data

db.matchElementInArrayDemo.insertMany([
    {
        "StudentName": "Chris",
        "StudentOtherDetails": [
            {"StudentCountryName": "US", "StudentSkills": "MongoDB"},
            {"StudentCountryName": "UK", "StudentSkills": "Java"}
        ]
    },
    {
        "StudentName": "Chris",
        "StudentOtherDetails": [
            {"StudentCountryName": "AUS", "StudentSkills": "PHP"},
            {"StudentCountryName": "US", "StudentSkills": "MongoDB"}
        ]
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cd423282cba06f46efe9ee2"),
        ObjectId("5cd423412cba06f46efe9ee3")
    ]
}

Display All Documents

db.matchElementInArrayDemo.find().pretty();

{
    "_id": ObjectId("5cd423282cba06f46efe9ee2"),
    "StudentName": "Chris",
    "StudentOtherDetails": [
        {
            "StudentCountryName": "US",
            "StudentSkills": "MongoDB"
        },
        {
            "StudentCountryName": "UK",
            "StudentSkills": "Java"
        }
    ]
}
{
    "_id": ObjectId("5cd423412cba06f46efe9ee3"),
    "StudentName": "Chris",
    "StudentOtherDetails": [
        {
            "StudentCountryName": "AUS",
            "StudentSkills": "PHP"
        },
        {
            "StudentCountryName": "US",
            "StudentSkills": "MongoDB"
        }
    ]
}

Match Array Elements

Find documents where array elements have either StudentCountryName as "US" OR StudentSkills as "MongoDB" ?

db.matchElementInArrayDemo.find({
    $or: [
        {"StudentOtherDetails.StudentCountryName": "US"},
        {"StudentOtherDetails.StudentSkills": "MongoDB"}
    ]
}).limit(1);

{
    "_id": ObjectId("5cd423282cba06f46efe9ee2"),
    "StudentName": "Chris",
    "StudentOtherDetails": [
        {
            "StudentCountryName": "US",
            "StudentSkills": "MongoDB"
        },
        {
            "StudentCountryName": "UK",
            "StudentSkills": "Java"
        }
    ]
}

Conclusion

Use $or operator with dot notation to match elements in arrays based on multiple field conditions. The query returns documents where any array element satisfies at least one of the specified criteria.