Потоците за промяна в MongoDB изискват набор от реплики, за да функционират.
Според документите на Mongoose:
mongoose.connect('mongodb://[username:[email protected]]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]' [, options]);
Пълен пример
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...');
}
Пълният пример е извлечен от https://thecodebarbarian.com /stock-price-notifications-with-mongoose-and-mongodb-change-streams