Program Statement

Develop a script that uses MongoDB's aggregation framework to perform operations like grouping, filtering, and sorting. For instance, aggregate user data to find the average age of users in different cities.

The Real MongoDB Aggregation Pipeline

Run this in mongosh after inserting sample documents into a users collection:

db.users.insertMany([
  { name: "Aman",  city: "Delhi",     age: 22 },
  { name: "Riya",  city: "Mumbai",    age: 27 },
  { name: "Kabir", city: "Delhi",     age: 30 },
  { name: "Sneha", city: "Bengaluru", age: 24 },
  { name: "Zoya",  city: "Mumbai",    age: 21 },
  { name: "Dev",   city: "Bengaluru", age: 29 }
]);

db.users.aggregate([
  { $group: { _id: "$city", avgAge: { $avg: "$age" } } },
  { $sort:  { avgAge: -1 } }
]);

Stages Used

Note

MongoDB needs a running mongod server — see Lab 0. The code below simulates the exact same pipeline in plain JavaScript over an in-memory array, so you can run it right now and see the identical grouped/sorted result.

CO Mapping

CO4