node_modules/mongoose/examples/querybuilder/querybuilder.js

// import async to make control flow simplier
var async = require('async');

// import the rest of the normal stuff
var mongoose = require('../../lib');

require('./person.js')();

var Person = mongoose.model('Person');

// define some dummy data
var data = [
  {
    name: 'bill',
    age: 25,
    birthday: new Date().setFullYear((new Date().getFullYear() - 25))
  },
  {
    name: 'mary',
    age: 30,
    birthday: new Date().setFullYear((new Date().getFullYear() - 30))
  },
  {
    name: 'bob',
    age: 21,
    birthday: new Date().setFullYear((new Date().getFullYear() - 21))
  },
  {
    name: 'lilly',
    age: 26,
    birthday: new Date().setFullYear((new Date().getFullYear() - 26))
  },
  {
    name: 'alucard',
    age: 1000,
    birthday: new Date().setFullYear((new Date().getFullYear() - 1000))
  }
];


mongoose.connect('mongodb://localhost/persons', function(err) {
  if (err) throw err;

  // create all of the dummy people
  async.each(data, function(item, cb) {
    Person.create(item, cb);
  }, function(err) {
    if (err) throw err;

    // when querying data, instead of providing a callback, you can instead
    // leave that off and get a query object returned
    var query = Person.find({age: {$lt: 1000}});

    // this allows you to continue applying modifiers to it
    query.sort('birthday');
    query.select('name');

    // you can chain them together as well
    // a full list of methods can be found:
    // http://mongoosejs.com/docs/api.html#query-js
    query.where('age').gt(21);

    // finally, when ready to execute the query, call the exec() function
    query.exec(function(err, results) {
      if (err) throw err;

      console.log(results);

      cleanup();
    });
  });
});

function cleanup() {
  Person.remove(function() {
    mongoose.disconnect();
  });
}