MongoDB aggregate query to sort

The $sort stage in MongoDB aggregation pipeline sorts documents by one or more fields. Use 1 for ascending order and -1 for descending order. You can combine it with other stages like $match to filter and sort results.

Syntax

db.collection.aggregate([
    { $match: { field: value } },
    { $sort: { field: 1 } }  // 1 for ascending, -1 for descending
]);

Sample Data

db.demo67.insertMany([
    { "StudentAge": 23 },
    { "StudentAge": 21 },
    { "StudentAge": 24 }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e289edf602d9a2ff1828ed8"),
        ObjectId("5e289ee1602d9a2ff1828ed9"),
        ObjectId("5e289ee3602d9a2ff1828eda")
    ]
}

Example 1: Sort in Descending Order

Filter students older than 20 and sort by age in descending order ?

db.demo67.aggregate([
    { $match: { "StudentAge": { $gt: 20 } } },
    { $sort: { "StudentAge": -1 } }
]);

{ "_id": ObjectId("5e289ee3602d9a2ff1828eda"), "StudentAge": 24 }
{ "_id": ObjectId("5e289edf602d9a2ff1828ed8"), "StudentAge": 23 }
{ "_id": ObjectId("5e289ee1602d9a2ff1828ed9"), "StudentAge": 21 }

Example 2: Sort in Ascending Order

Sort all students by age in ascending order ?

db.demo67.aggregate([
    { $sort: { "StudentAge": 1 } }
]);

{ "_id": ObjectId("5e289ee1602d9a2ff1828ed9"), "StudentAge": 21 }
{ "_id": ObjectId("5e289edf602d9a2ff1828ed8"), "StudentAge": 23 }
{ "_id": ObjectId("5e289ee3602d9a2ff1828eda"), "StudentAge": 24 }

Key Points

• $sort can be used with or without $match filtering
• Use 1 for ascending order and -1 for descending order
• Sort operations are performed after filtering when combined with $match

Conclusion

The $sort stage in MongoDB aggregation pipeline effectively sorts documents by specified fields. Combine it with $match to filter and sort results in a single query operation.