Basic REST + mongoose + express3 setup.

Post.js

/**
 * Model that  represents a post that has been approved by an admin
 * @type {Model}
 */
var mongoose = require('mongoose');

var Post = new mongoose.Schema({
  "id": {type: String, required: true, unique: true},
  "source": { type: String, enum: ["twitter", "instagram"], required:true },
  "tag": {type: String, required: true},
  "type": { type: String, enum: ["video", "image"], required:true },
  "media": {type: mongoose.SchemaTypes.Url, required: true},
  "username": {type: String, required: true},
  "user_image": {type: mongoose.SchemaTypes.Url, required: true},
  "caption": {type: String, required: true},
  "post_date": {type: Date required: true},
  "approved": Boolean
});

module.exports = mongoose.model('Post', Post);

server.js

var mers = require('mers'),
  mongoose = require('mongoose'),
  mongooseTypes = require("mongoose-types"),
  express = require('express')
  app = express();

var port = Number(process.env.PORT || 5000);
app.listen(port);
console.log('Listening on http://0.0.0.0:' + port);

if (!process.env.MONGOLAB_URI){
  console.log('Please set the environment variable MONGOLAB_URI.');
  process.exit(1);
}

mongoose.connect(process.env.MONGOLAB_URI);
mongoose.connection.on('error', function(e){
  console.log('Mongoose Error:', e)
});

// load extra field-types: Email & Url
mongooseTypes.loadTypes(mongoose);

// load models
var Post = require('./Post');

// load mers REST interface: https://github.com/jspears/mers
app.use('/api', mers({mongoose:mongoose}).rest());

//  static webserver in pub/
app.use(express.static(path.join(__dirname, 'pub')));