What is the MongoDB aggregation pipeline in Node.js?

Can you explain what the MongoDB aggregation pipeline is and how to use it in Node.js?

The MongoDB aggregation pipeline is a framework for data aggregation that processes data records and returns computed results. In Node.js, you can use it with the MongoDB driver to perform operations like filtering, grouping, and sorting data.

How do I set up a basic aggregation pipeline in my Node.js application?

To set up a basic aggregation pipeline, first, ensure you have the MongoDB Node.js driver installed. Then, you can create an aggregation pipeline using the aggregate() method on your collection. For example: db.collection.aggregate([{ $match: { status: 'active' } }, { $group: { _id: '$category', total: { $sum: 1 } } }]).

What are some common stages used in the aggregation pipeline?

Common stages include $match for filtering, $group for grouping data, $sort for ordering results, and $project for reshaping documents.

Can you give me an example of a more complex aggregation pipeline?

Sure! A complex pipeline might look like this: db.collection.aggregate([{ $match: { status: 'active' } }, { $group: { _id: '$category', total: { $sum: '$amount' } } }, { $sort: { total: -1 } }]) which matches active records, groups by category, and sorts by total amount.