mongo_image.js

var express = require('express');
var fs = require('fs');
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

// connect to mongo
mongoose.connect('localhost', 'img_db');

// example schema
var schema = new Schema({
    img: { data: Buffer, contentType: String }
});

// our model
var A = mongoose.model('A', schema);

mongoose.connection.on('open', function () {
  console.log('mongo is open');

  // empty the collection
  A.remove(function (err) {
    if (err) throw err;

    console.error('removed old docs');

    // store an img in binary in mongo
    var a = new A;
    a.img.data = "YOUR IMAGE RETRIEVED FROM AN ENDPOINT" ;
    a.img.contentType = 'image/png';
    a.save(function (err, a) {
      if (err) throw err;

      console.error('saved img to mongo');

      // start a demo server
      var server = express.createServer();
      server.get('/', function (req, res, next) {
        A.findById(a, function (err, doc) {
          if (err) return next(err);
          res.contentType(doc.img.contentType);
          res.send(doc.img.data);
        });
      });

      server.listen(3333, function (err) {
        var address = server.address();
        console.log('server listening on http://%s:%d', address.address, address.port);
      });
    });
  });

});