Write a MongoDB query to get nested value?

You can use dot notation to query nested values in MongoDB documents. Dot notation allows you to access fields within embedded documents using the format parentField.nestedField.

Syntax

db.collection.find({"parentField.nestedField": "value"});

Sample Data

Let us first create a collection with nested documents ?

db.nestedQueryDemo.insertMany([
    {
        "EmployeeName": "John",
        "EmployeeDetails": {
            "_id": "EMP-101",
            "EmployeeAge": 23,
            "EmployeeCompanyName": "IBM"
        }
    },
    {
        "EmployeeName": "Carol",
        "EmployeeDetails": {
            "_id": "EMP-110",
            "EmployeeAge": 29,
            "EmployeeCompanyName": "Amazon"
        }
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5c9ea31dd628fa4220163b69"),
        ObjectId("5c9ea36bd628fa4220163b6a")
    ]
}

Display All Documents

db.nestedQueryDemo.find().pretty();

{
    "_id": ObjectId("5c9ea31dd628fa4220163b69"),
    "EmployeeName": "John",
    "EmployeeDetails": {
        "_id": "EMP-101",
        "EmployeeAge": 23,
        "EmployeeCompanyName": "IBM"
    }
}
{
    "_id": ObjectId("5c9ea36bd628fa4220163b6a"),
    "EmployeeName": "Carol",
    "EmployeeDetails": {
        "_id": "EMP-110",
        "EmployeeAge": 29,
        "EmployeeCompanyName": "Amazon"
    }
}

Query Nested Value

Find documents where the nested employee ID is "EMP-110" ?

db.nestedQueryDemo.find({"EmployeeDetails._id": "EMP-110"}).pretty();

{
    "_id": ObjectId("5c9ea36bd628fa4220163b6a"),
    "EmployeeName": "Carol",
    "EmployeeDetails": {
        "_id": "EMP-110",
        "EmployeeAge": 29,
        "EmployeeCompanyName": "Amazon"
    }
}

More Examples

Query by nested age field ?

db.nestedQueryDemo.find({"EmployeeDetails.EmployeeAge": {$gt: 25}});

Query by nested company name ?

db.nestedQueryDemo.find({"EmployeeDetails.EmployeeCompanyName": "IBM"});

Conclusion

Use dot notation to access nested document fields in MongoDB queries. Simply combine the parent field name and nested field name with a dot to query embedded document values effectively.