(node:89372) DeprecationWarning: Calling an asynchronous function without callback is deprecated.

// read.js

var Db = require('mongodb').Db,
MongoClient = require('mongodb').MongoClient,
Server = require('mongodb').Server,
ReplSetServers = require('mongodb').ReplSetServers,
ObjectID = require('mongodb').ObjectID,
Binary = require('mongodb').Binary,
GridStore = require('mongodb').GridStore,
Grid = require('mongodb').Grid,
Code = require('mongodb').Code,
fs = require('fs'),
assert = require('assert');

var db = new Db('test', new Server('localhost', 27017));
// Establish connection to db
db.open(function(err, db) {
// Our file ID
var fileId = new ObjectID();

// Open a new file
var gridStore = new GridStore(db, fileId, 'w');

// Read the filesize of file on disk (provide your own)
var fileSize = fs.statSync('./surfer.png').size;
// Read the buffered data for comparision reasons
var data = fs.readFileSync('./surfer.png');

// Open the new file
gridStore.open(function(err, gridStore) {

// Write the file to gridFS
gridStore.writeFile('./surfer.png', function(err, doc) {

  // Read back all the written content and verify the correctness
  GridStore.read(db, fileId, function(err, fileData) {
    assert.equal(data.toString('base64'), fileData.toString('base64'))
    assert.equal(fileSize, fileData.length);

    db.close();
  });
});
});
});