You’re staring at your assignment, and the words “aggregation pipeline” practically jump off the page. You’ve written a few MongoDB queries before—maybe a find() , maybe a sort() —but this? $match , $group , $project ? They all blend together, and honestly, you’re not even sure where to start. I’ve been there, and for a while, I thought I’d never get an aggregation pipeline working for my class project. The thing is, once you get the pieces, it actually clicks—and I want to show you exactly how I got mine working, what tripped me up, and how you can avoid the same headaches. What Even Is an Aggregation Pipeline? Before I sorted this out, aggregation pipelines just sounded intimidating. Here’s the simplest way to think about them: an aggregation pipeline in MongoDB is just a way of processing your data step by step, like an assembly line. You send your documents (think: JSON objects) through a series of “stages,” each one transforming or filtering your data, until you get exactly what you need.…