DeprecationWarning: GridStore is deprecated

mongodb version is 3.1.1

(node:65150) DeprecationWarning: GridStore is deprecated, and will be removed in a future version. Please use GridFSBucket instead

[stevenlobo]

The mongoose docs at https://mongoosejs.com/docs/deprecations.html#-gridstore- indicates the reason for the depreciation warning and path forward:

That is because gridfs-stream relies on a deprecated MongoDB driver class. 
You should instead use the MongoDB driver's own streaming API 

// Replace this:
const conn = mongoose.createConnection('mongodb://localhost:27017/gfstest');
const gfs = require('gridfs-store')(conn.db);
const writeStream = gfs.createWriteStream({ filename: 'test.dat' });

// With this:
const conn = mongoose.createConnection('mongodb://localhost:27017/gfstest');
const gridFSBucket = new mongoose.mongo.GridFSBucket(conn.db);
const writeStream = gridFSBucket.openUploadStream('test.dat');

There is also a link on that site that provides usage examples of GridFSBucket.

[Yaxian]

  import {GridFSBucket, MongoClient, ObjectId} from 'mongodb';
  import { Readable } from 'stream';

  let connection = MongoClient.connect(url, { 
       useNewUrlParser: true,
       useUnifiedTopology: true
   } );
  let db = connection.db(dbName);
  let gridfsBucket = new GridFSBucket(db, {bucketName: bucketName});
  let downloadStream = gridfsBucket.openDownloadStream(new ObjectId(_id));

  let buffer = [];
  downloadStream.on('data', (chunk) => {
       buffer.push(chunk);
  });
  downloadStream.on('end', () => {
       let readable = new Readable();
       readable._read = () => {};
       readable.push(Buffer.concat(buffer));
       readable.push(null);
  });