How can we automatically update a MongoDB collection at midnight with the top performing data from various collections?

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To automatically update a MongoDB collection at midnight with the top performing data from various collections, you can use the MongoDB Aggregation Pipeline and a Cron job.

Here are the steps to follow:

1. Create an aggregation pipeline that selects the top performing data from all the collections you want to include. This pipeline can use operators like $sort, $group, $limit, and $lookup to gather and aggregate the data.

2. Create a new collection to store the aggregated data.

3. Set up a Cron job that runs at midnight and triggers a script to execute your aggregation pipeline and update the new collection.

Here's some sample code to give you an idea of what this might look like:

const MongoClient = require('mongodb').MongoClient;
const cron = require('node-cron');

// Define the MongoDB URI and database name
const uri = 'mongodb://localhost:27017';
const dbName = 'myDatabase';

// Set up the Cron job to run at midnight
cron.schedule('0 0 * * *', () => {
  // Connect to the MongoDB database
  MongoClient.connect(uri, (err, client) => {
    if (err) throw err;
    const db = client.db(dbName);

    // Define the aggregation pipeline to select the top performing data
    const pipeline = [
      { $sort: { performance: -1 } },
      { $group: { _id: '$group', top: { $first: '$$ROOT' } } },
      { $replaceRoot: { newRoot: '$top' } }
      // Add more stages here as needed
    ];

    // Execute the aggregation pipeline and update the new collection
    db.collection('newCollection').aggregate(pipeline).toArray((err, result) => {
      if (err) throw err;
      db.collection('updatedCollection').insertMany(result, (err, res) => {
        if (err) throw err;
        console.log(`${res.insertedCount} documents inserted into updatedCollection.`);
        client.close();
      });
    });
  });
});

Note that this is just an example, and you'll need to customize it to fit your specific use case. You may also want to add error handling and logging to ensure that everything runs smoothly.