How to reach subdata in MongoDB and display a particular document?

To reach subdata in MongoDB and display a particular document, use dot notation to access nested fields. This allows you to query specific values within nested objects and retrieve matching documents.

Syntax

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

Sample Data

Let us create a collection with nested documents ?

db.demo450.insertMany([
    {"Information": {"StudentDetails": {"StudentName": "Chris", "StudentAge": 21}}},
    {"Information": {"StudentDetails": {"StudentName": "David", "StudentAge": 23}}},
    {"Information": {"StudentDetails": {"StudentName": "Mike", "StudentAge": 22}}}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e7b590e71f552a0ebb0a6e6"),
        ObjectId("5e7b591a71f552a0ebb0a6e7"),
        ObjectId("5e7b592271f552a0ebb0a6e8")
    ]
}

Display all documents from the collection ?

db.demo450.find();

{ "_id": ObjectId("5e7b590e71f552a0ebb0a6e6"), "Information": { "StudentDetails": { "StudentName": "Chris", "StudentAge": 21 } } }
{ "_id": ObjectId("5e7b591a71f552a0ebb0a6e7"), "Information": { "StudentDetails": { "StudentName": "David", "StudentAge": 23 } } }
{ "_id": ObjectId("5e7b592271f552a0ebb0a6e8"), "Information": { "StudentDetails": { "StudentName": "Mike", "StudentAge": 22 } } }

Example: Query Subdata Using Dot Notation

Find the document where the nested StudentName is "David" ?

db.demo450.find({"Information.StudentDetails.StudentName": "David"});

{ "_id": ObjectId("5e7b591a71f552a0ebb0a6e7"), "Information": { "StudentDetails": { "StudentName": "David", "StudentAge": 23 } } }

Key Points

• Use dot notation to access nested fields: "parentField.childField"
• MongoDB traverses the document hierarchy using the specified path
• This method works for any level of nesting depth

Conclusion

Dot notation provides a simple way to query nested documents in MongoDB. Use the full path from parent to target field to retrieve specific documents based on subdata values.