Change Streams によるデータの監視

1// Watch for changes in a collection by using a change stream2import { MongoClient } from "mongodb";3
4// Replace the uri string with your MongoDB deployment's connection string.5const uri = "<connection string uri>";6
7const client = new MongoClient(uri);8
9// Declare a variable to hold the change stream10let changeStream;11
12// Define an asynchronous function to manage the change stream13async function run() {14  try {15    const database = client.db("insertDB");16    const haikus = database.collection("haikus");17
18    // Open a Change Stream on the "haikus" collection19    changeStream = haikus.watch();20
21    // Print change events as they occur22    for await (const change of changeStream) {23      console.log("Received change:\n", change);24    }25    // Close the change stream when done26    await changeStream.close();27    28  } finally {29    // Close the MongoDB client connection30    await client.close();31  }32}33run().catch(console.dir);

Received change:{  _id: {    _data: '...'  },  operationType: 'insert',  clusterTime: new Timestamp({ t: 1675800603, i: 31 }),  fullDocument: {    _id: new ObjectId("..."),    ...  },  ns: { db: 'insertDB', coll: 'haikus' },  documentKey: { _id: new ObjectId("...") }}

1/* Change stream listener */2
3import { MongoClient } from "mongodb";4
5// Replace the uri string with your MongoDB deployment's connection string6const uri = "<connection string uri>";7
8const client = new MongoClient(uri);9
10const simulateAsyncPause = () =>11  new Promise(resolve => {12    setTimeout(() => resolve(), 1000);13  });14
15let changeStream;16async function run() {17  try {18    const database = client.db("insertDB");19    const haikus = database.collection("haikus");20
21    // Open a Change Stream on the "haikus" collection22    changeStream = haikus.watch();23
24    // Set up a change stream listener when change events are emitted25    changeStream.on("change", next => {26      // Print any change event27      console.log("received a change to the collection: \t", next);28    });29
30    // Pause before inserting a document31    await simulateAsyncPause();32
33    // Insert a new document into the collection34    await myColl.insertOne({35      title: "Record of a Shriveled Datum",36      content: "No bytes, no problem. Just insert a document, in MongoDB",37    });38
39    // Pause before closing the change stream40    await simulateAsyncPause();41
42    // Close the change stream and print a message to the console when it is closed43    await changeStream.close();    44    console.log("closed the change stream");45  } finally {46    // Close the database connection on completion or error47    await client.close();48  }49}50run().catch(console.dir);