MongoDB watch () để quan sát sự thay đổi trong Cơ sở dữ liệu với NodeJS và Mongoose

Các luồng thay đổi trong MongoDB yêu cầu một tập hợp bản sao để hoạt động.

Theo Mongoose docs:

mongoose.connect('mongodb://[username:[email protected]]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]' [, options]);

Ví dụ đầy đủ

const { ReplSet } = require('mongodb-topology-manager');
const mongoose = require('mongoose');

run().catch(error => console.error(error));

async function run() {
  // Make sure you're using mongoose >= 5.0.0
  console.log(new Date(), `mongoose version: ${mongoose.version}`);

  await setupReplicaSet();

  // Connect to the replica set
  const uri = 'mongodb://localhost:31000,localhost:31001,localhost:31002/' +
    'test?replicaSet=rs0';
  await mongoose.connect(uri);
  // For this example, need to explicitly create a collection, otherwise
  // you get "MongoError: cannot open $changeStream for non-existent database: test"
  await mongoose.connection.createCollection('Person');

  // Create a new mongoose model
  const personSchema = new mongoose.Schema({
    name: String
  });
  const Person = mongoose.model('Person', personSchema, 'Person');

  // Create a change stream. The 'change' event gets emitted when there's a
  // change in the database
  Person.watch().
    on('change', data => console.log(new Date(), data));

  // Insert a doc, will trigger the change stream handler above
  console.log(new Date(), 'Inserting doc');
  await Person.create({ name: 'Axl Rose' });
  console.log(new Date(), 'Inserted doc');
}

// Boilerplate to start a new replica set. You can skip this if you already
// have a replica set running locally or in MongoDB Atlas.
async function setupReplicaSet() {
  const bind_ip = 'localhost';
  // Starts a 3-node replica set on ports 31000, 31001, 31002, replica set
  // name is "rs0".
  const replSet = new ReplSet('mongod', [
    { options: { port: 31000, dbpath: `${__dirname}/data/db/31000`, bind_ip } },
    { options: { port: 31001, dbpath: `${__dirname}/data/db/31001`, bind_ip } },
    { options: { port: 31002, dbpath: `${__dirname}/data/db/31002`, bind_ip } }
  ], { replSet: 'rs0' });

  // Initialize the replica set
  await replSet.purge();
  await replSet.start();
  console.log(new Date(), 'Replica set started...');
}

Ví dụ đầy đủ được trích từ https://thecodebarbarian.com / stock-price-notification-with-mongoose-and-mongodb-change-stream