foo.js

function Foo (id) {
  var _this = this;
  if (id) {
    db.redis.get(id, function(err, res) {
      var obj = JSON.parse(res);
      for (property in obj) {
        if (property === 'date_created') {
          _this[property] = new Date(obj[property]);
        } else {
          _this[property] = obj[property];
        }
        console.log(_this[property]);
      }
    });
  } else {
    this.date_created = new Date();
    this.id = createId(this.date_created.toString());
    db.redis.set(this.id, JSON.stringify(this));
  }

  return this;
}