Example using the mongodb-native module and step to write to mongodb gridfs

gridstoretest.js

var Db = require('mongodb').Db,
Connection = require('mongodb').Connection,
Server = require('mongodb').Server,
GridStore = require('mongodb').GridStore,
Step = require('step'),
Sys = require('sys'),
Fs = require('fs');

var database;

Step(
  function openDb() {
    var db1 = new Db('node-mongo-examples', new Server('localhost', Connection.DEFAULT_PORT, {}), {native_parser:true});
    db1.open(this);
  },

  function opendStore(err, db) {
    if (err) throw err;

    database = db;
    var gridStore = new GridStore(db, "somepicture", "w", {
        'content_type': 'image/jpeg', 
        'metadata': { 'tes0r': 2342 },
        'root': 'images'
      });

    gridStore.open(this.parallel());
    Fs.readFile('./201713246bbfb9efde162aee3b14ec0b3d4101d4.jpg', this.parallel());
  },

  function writeToGridStore(err, gridStore, image) {
    if (err) throw err;
    gridStore.write(image, this);
  },

  function closeStore(err, gridStore) {
    if (err) throw err;
    gridStore.close(this);
  },

  function reOpenStore(err, result) {
    var gridStore = new GridStore(database, "somepicture", "w", { 
        'root': 'images'
      });
    gridStore.open(this);
  },

  function readFromStore(err, gridStore) {
    if (err) throw err;

    Sys.puts("contentType: " + gridStore.contentType);
    Sys.puts("uploadDate: " + gridStore.uploadDate);
    Sys.puts("chunkSize: " + gridStore.chunkSize);
    Sys.puts("metadata: " + Sys.inspect(gridStore.metadata));          

    gridStore.close(this);
  },

  function finish(err, result) {
    if (err) throw err;

    console.dir(result);

    database.close();
  }

);