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Flexible non-magical wrapper for the nodejs MongoDB driver
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Flexible wrapper for the nodejs mongoDB driver. Its not a ORM, but it can be used to handle the logic of your models. No magic, no pain.


$ npm install mongolia

Mongolia contains two independent modules:

  • model: An object representing a collection with some hooks of mongoDB calls.
  • validator: An object that validates mongoDB documents and returns errors if found.


Each model has a colection name and a reference to the database.

Models don't map data from mongoDB, they are just a layer to centralize all the logic.

module.exports = function (db) {
  // our user model will do mongoDB calls using 'users' collection
  var USER = require('mongolia').model(db, 'users');

  // implement some user logic

  return USER;

mongoDB commands

Calls to the database are done using the function mongo. Mongolia supports all the collection methods defiend on the driver plus some custom methods.

var Db = require('mongodb/lib/mongodb/db').Db,
    Server = require('mongodb/lib/mongodb/connection').Server,
    db = new Db('blog', new Server('localhost', 27017, {auto_reconnect: true, native_parser: true})); () {

    var User = require('./user.js')(db);
    User.mongo('find', {name: 'foo'}, function (error, user) {


All the collection methods from the driver are supported.

If you need more information visit the driver documentation

Custom mongoDB commands

Mongolia provides some useful commands that are not available using the driver.

  • findArray: find that returns an array instead of a cursor.
  • mapReduceArray: mapReduce that returns an array with the results.
  • mapReduceCursor: mapReduce that returns a cursor.


Mongolia let you define some hooks on your models that will be triggered after a mongoDB command.

  • onCreate(document, callback): triggered before an insert. If multiples documents are inserted, it will be called for each of them.
  • afterCreate(document, callback): triggered after an `insert. If multiples documents are inserted, it will be called for each of them.
  • onUpdate(update, callback): triggered before an update or findAndModify command.
  • afterUpdate(update, callback): triggered after an update or findAndModify command.


module.exports = function (db) {
  var COMMENT = require('mongolia').model(db, 'comments');

  COMMENT.onCreate = function (document) {
    document.created_at = new Date();

  COMMENT.atferCreate = function (document) {
    var post = require('./post')(this.db);
    post.mongo('update', {_id: document.post_id}, {'$inc': {num_posts: 1}});

  return COMMENT;

Embedded documents

Mongolia helps you to denormalize your mongoDB database.


Filters document following the skeletons directive.

getEmbeddedDocument(name, object, scope);


module.exports = function (db) {
  var POST = require('mongolia').model(db, 'posts');

  // only embed the comment's _id, and title
  POST.skeletons= {
    comment: ['_id', 'title']

  return POST;

var comment = {'_id': 1, title: 'foo', body: 'Lorem ipsum'}
console.log(Post(db).getEmbeddedDocument('comment', comment));
// outputs => {'_id': 1, title: 'foo'};

console.log(Post(db).getEmbeddedDocument('comment', comment, 'post.comment'));
// outputs => {'post.comment._id': 1, 'post.comment.title': 'foo'};


Updates an embed object.

updateEmbeddedDocument(id, document_name, document, options, callback);


module.exports = function (db) {
  var USER = require('mongolia').model(db, 'users');

  // After updating a user, we want to update denormalized foreach post
  USER.afterUpdate = function (document, update) {
    Post(db).updateEmbeddedDocument(document._id, 'author', update);

  return USER;


Pushes an embed object.

pushEmbedObject(model, data, name, options, callback);


module.exports = function (db) {
  var POST = require('mongolia')(db, 'posts');

  // After creating a post, we want to push it to `users.posts[]`
  POST.afterCreate = function (document) {
    User(db).pushEmbedObject(, 'posts', document);

  return POST;

Create and update instances

Mongolia provides with two methods that allow you to create and update using the validator.

validateAndInsert(document, callback(error, validator));
validateAndUpdate(document, update, callback(error, validator));

In order to validate an insertion/update, the model have to implement a validate function on your model.

validate(document, update, callback);


// post.js
module.exports = function (db) {
  var POST = require('mongolia').model(db, 'posts');

  POST.validate = function (document, update, callback) {
    var validator = require('mongolia').validator(document, data);

      title: [validator.regex.title, 'Incorrect title'],
      body: [/.{4,200}/, 'Incorrect body'],

    if (!update.body === 'Lorem ipsum') {
      validator.addError('body', 'You can be a little bit more creative');

    callback(null, validator);

  return POST;

// app.js
var Post = require('./post.js');

  {title: 'This is a post', body: 'Lorem ipsum'},
  function (error, validator) {
    if (validator.hasErrors()) {
    } else {



Returns true if the validator is handling an updateInstance operation.


Returns true if the validator is handling an createInstance operation.


Returns true if the attributed changed

addError(field, value)

Adds an error to your validator. Accept dot notation to add nested errors.


Returns true if the attributed failed a validation. Accept dot notation to check nested errors.


Returns true if any attributed failed a validation


It fills your validator with errors if any of the elements are empty


It fills your validator with errors if any of the elements fail the regex


It fills your validator with errors if any of the elements fail the confirmation (good for passwords)

validateQuery(validations, callback)

It fills your validator with errors if any of the queries fail (good to avoid duplicated data)

Example using some of the validator features:

var User = function (db) {
  var USER = require('mongolia').model(db, 'users');

  USER.validate = function (element, data, callback) {
    var validator = require('mongolia').validator(element, data);

      name: [validator.regex.username, 'Incorrect name'],
      email: [, 'Incorrect email'],
      password: [validator.regex.password, 'Incorrect password'],
      description: [validator.regex.description, 'Incorrect description']

    if (validator.attrChanged('password')) {
        'password': ['password_confirmation', 'Passwords must match']

    if (!data.tags || data.tags.length <= 0) {
      validator.addError('tags', 'Select at least one tag');

    if (validator.isUpdating()) {
        name: [this, {name:}, false, 'There is already a user with this name'],
        email: [this, {email:}, false, 'There is already a user with this email']
      }, function () {
        callback(null, validator);
    } else {
      callback(null, validator);

  return USER;
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