MongoDB - How can I see if all elements of a field are contained in a superset?

To check if all elements of an array field are contained within a superset in MongoDB, use the $not operator combined with $elemMatch and $nin. This ensures no array element exists outside the specified superset.

Syntax

db.collection.find({
    "arrayField": {
        $not: {
            $elemMatch: {
                $nin: ["superset", "values", "here"]
            }
        }
    }
});

Sample Data

db.demo624.insertMany([
    {"ListOfName": ["John", "Chris", "David", "Bob"]},
    {"ListOfName": ["John", "Chris"]},
    {"ListOfName": ["John", "Chris", "Carol"]},
    {"ListOfName": ["John", "Chris", "Bob"]},
    {"ListOfName": ["John", "Chris", "Mike", "Robert"]}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e9ab3ff6c954c74be91e6a5"),
        ObjectId("5e9ab4026c954c74be91e6a6"),
        ObjectId("5e9ab4076c954c74be91e6a7"),
        ObjectId("5e9ab40e6c954c74be91e6a8"),
        ObjectId("5e9ab4186c954c74be91e6a9")
    ]
}

Example: Find Documents with Elements in Superset

Find documents where all names in ListOfName are contained in the superset ["John", "Chris", "David", "Bob"] ?

db.demo624.find({
    "ListOfName": {
        $not: {
            $elemMatch: {
                $nin: ["John", "Chris", "David", "Bob"]
            }
        }
    }
});

{ "_id": ObjectId("5e9ab3ff6c954c74be91e6a5"), "ListOfName": ["John", "Chris", "David", "Bob"] }
{ "_id": ObjectId("5e9ab4026c954c74be91e6a6"), "ListOfName": ["John", "Chris"] }
{ "_id": ObjectId("5e9ab40e6c954c74be91e6a8"), "ListOfName": ["John", "Chris", "Bob"] }

How It Works

• $nin finds elements NOT in the superset
• $elemMatch matches arrays containing at least one element NOT in the superset
• $not inverts the result, returning only arrays where ALL elements ARE in the superset

Conclusion

Use $not: {$elemMatch: {$nin: [superset]}} to find documents where all array elements exist within a specified superset. This pattern efficiently filters arrays to ensure complete subset containment.