use mongoose aggregation in javascript

Mongoose provides a powerful way to perform aggregation queries on MongoDB. Aggregation queries are used to analyze data and return calculated results. The Mongoose aggregate function takes an array of stages as its argument, each stage being a separate operation that is performed on the data.

Here's an example of using Mongoose aggregation to find the total amount of sales for each product category in a collection of sales records:

index.tsx
const Sales = require('./models/sales');

Sales.aggregate([
  {$group: {_id: '$productCategory', totalSales: {$sum: '$amount'}}}
]).exec((err, result) => {
  if (err) {
    console.error(err);
    return;
  }
  console.log(result);
});
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In this query, we first use the $group stage to group the results by productCategory. The _$id field is used to define the grouping key. We then use the $sum operator to calculate the total sales for each group, which we store in the totalSales field.

The exec function runs the query and returns the results. If there is an error, we log it to the console. Otherwise, we log the results to the console.

This is just one example of what you can do with Mongoose aggregation. There are many other stages and operators available, which you can use to perform more complex analysis on your data.