How to get all docs which contain another doc in an array with MongoDB?

To get all documents which contain another document in an array, use dot notation with the find() method in MongoDB. This allows you to query nested fields within array elements.

Syntax

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

Sample Data

Let us create a collection with documents containing nested objects in arrays ?

db.demo465.insertMany([
    {
        id: 101,
        details: [
            {
                Name: "Chris",
                Info: {
                    Subject: "MongoDB",
                    Marks: 67
                }
            },
            {
                Name: "David",
                Info: {
                    Subject: "MySQL",
                    Marks: 78
                }
            }
        ]
    },
    {
        id: 102,
        details: [
            {
                Name: "Bob",
                Info: {
                    Subject: "Java",
                    Marks: 45
                }
            },
            {
                Name: "Carol",
                Info: {
                    Subject: "C",
                    Marks: 67
                }
            }
        ]
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e80421bb0f3fa88e2279061"),
        ObjectId("5e80421cb0f3fa88e2279062")
    ]
}

Display All Documents

db.demo465.find();

{
    "_id": ObjectId("5e80421bb0f3fa88e2279061"),
    "id": 101,
    "details": [
        { "Name": "Chris", "Info": { "Subject": "MongoDB", "Marks": 67 } },
        { "Name": "David", "Info": { "Subject": "MySQL", "Marks": 78 } }
    ]
}
{
    "_id": ObjectId("5e80421cb0f3fa88e2279062"),
    "id": 102,
    "details": [
        { "Name": "Bob", "Info": { "Subject": "Java", "Marks": 45 } },
        { "Name": "Carol", "Info": { "Subject": "C", "Marks": 67 } }
    ]
}

Example: Query Documents Containing Specific Nested Document

Find all documents where the details array contains a document with Name "Bob" ?

db.demo465.find({"details.Name": "Bob"});

{
    "_id": ObjectId("5e80421cb0f3fa88e2279062"),
    "id": 102,
    "details": [
        { "Name": "Bob", "Info": { "Subject": "Java", "Marks": 45 } },
        { "Name": "Carol", "Info": { "Subject": "C", "Marks": 67 } }
    ]
}

Key Points

• Use arrayField.nestedField syntax to query nested documents in arrays
• MongoDB automatically searches through all array elements for matching values
• Returns the entire parent document when a match is found

Conclusion

Dot notation provides an efficient way to query documents containing specific nested objects in arrays. Use "arrayField.nestedField": value syntax to find documents where array elements match your criteria.