Generic MongoDB lib for use with Express 4 apps

db.js

'use strict';

var db,
    MongoClient = require('mongodb').MongoClient;

var database_name = checkExists(process.env.MONGODB_DATABASE) ? process.env.MONGODB_DATABASE : 'test',
    env_user      = process.env.MONGODB_USER,
    env_pass      = process.env.MONGODB_PASSWORD,
    env_host      = checkExists(process.env.MONGODB_HOST) ? process.env.MONGODB_HOST : 'localhost',
    env_port      = checkExists(process.env.MONGODB_PORT) ? parseInt(process.env.MONGODB_PORT, 10) : 27017;

var connString = env_host + ":" + env_port + "/" + database_name;

if (checkExists(env_user)) {
  connString = env_user + ":" + env_pass + "@" + connString;
}

MongoClient.connect("mongodb://" + connString,
  function(err, database) {
    if (!database) {
      console.log('eeeek! no database!');
    } else {
      db = database;
      console.log('using database: ' + database_name + ' on ' + env_host + ':' + env_port);
    }
  }
);

module.exports = {

  remove: function(name, query, callback) {
    db.collection(name).remove(query, callback);
  },

  removeOne: function(name, item, callback) {
    module.exports.remove(name, item, function(err, items) {
      callback(err, items[0]);
    });
  },

  find: function(name, query, limit, callback) {
    db.collection(name)
    .find(query)
    .sort({created: -1})
    .limit(limit)
    .toArray(callback);
  },

  findOne: function(name, query, callback) {
    db.collection(name).findOne(query, callback);
  },

  insert: function(name, items, callback) {
    db.collection(name).insert(items, callback);
  },

  // inserts a single document and returns it to the caller
  insertOne: function(name, item, callback) {
    module.exports.insert(name, item, function(err, items) {
      callback(err, items[0]);
    });
  },

  // update using id property of an item
  // return the item to the caller via findOne
  updateById: function(name, id, updateQuery, callback) {
    db.collection(name).update({id: id},
                               {$set: updateQuery},
      function(err, count) {
        module.exports.findOne(name, {id: id}, callback)
      });
  },

  // update using a query selector
  // return the item to the caller via findOne
  updateByQuery: function(name, selectorQuery, updateQuery, callback) {
    db.collection(name).update(selectorQuery,
                               {$set: updateQuery},
      function(err, count) {
        module.exports.findOne(name, selectorQuery, callback)
      });
  }

}

// unexported

function checkExists(x) { return x != null };

Uses the 'new' style of the MongoClient and conventions for node driver 1.4.7.