MongoDB query to find data from an array inside an object?

To find data from an array inside an object in MongoDB, use dot notation to navigate through the nested object structure and target the specific array field.

Syntax

db.collection.find({"objectField.arrayField": "searchValue"});

Sample Data

Let us first create a collection with documents ?

db.findDataDemo.insertMany([
    {
        "CustomerName": "John",
        "CustomerDetails": {
            "CountryName": ["AUS"],
            "isMarried": [false]
        }
    },
    {
        "CustomerName": "Carol",
        "CustomerDetails": {
            "CountryName": ["UK"],
            "isMarried": [true]
        }
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cefa5eeef71edecf6a1f6a5"),
        ObjectId("5cefa60aef71edecf6a1f6a6")
    ]
}

View Sample Data

db.findDataDemo.find().pretty();

{
    "_id": ObjectId("5cefa5eeef71edecf6a1f6a5"),
    "CustomerName": "John",
    "CustomerDetails": {
        "CountryName": ["AUS"],
        "isMarried": [false]
    }
}
{
    "_id": ObjectId("5cefa60aef71edecf6a1f6a6"),
    "CustomerName": "Carol",
    "CustomerDetails": {
        "CountryName": ["UK"],
        "isMarried": [true]
    }
}

Example: Query Array Inside Object

Find documents where the CountryName array contains "UK" ?

db.findDataDemo.find({"CustomerDetails.CountryName": "UK"});

{
    "_id": ObjectId("5cefa60aef71edecf6a1f6a6"),
    "CustomerName": "Carol",
    "CustomerDetails": {
        "CountryName": ["UK"],
        "isMarried": [true]
    }
}

Key Points

• Use dot notation to access nested fields: "object.array"
• MongoDB automatically searches within array elements for matching values
• No special array operators needed for simple value matching

Conclusion

Use dot notation with the format "objectField.arrayField" to query arrays nested inside objects. MongoDB will automatically search through the array elements to find matching documents.