Using Underscore.js with MongoDB

gistfile1.rb

require 'mongo'
require 'ap'

include Mongo

# Create a connection to a local MongdDB Instance
db = Connection.new.db('underscore-demo')

# Read and eval Underscore.js
underscore = File.read('underscore-min.js')
db.eval(underscore)

# Create some sample data
db['cars'].save({:make => 'Chevy', :model => 'Corvette', :year => 2011})
db['cars'].save({:make => 'Chevy', :model => 'Corvette', :year => 2010})
db['cars'].save({:make => 'Chevy', :model => 'Camero', :year => 2011})
db['cars'].save({:make => 'Toyota', :model => 'Camry', :year => 2011})

# Group by make with an array of models using _.any
result = db['cars'].group([:make], nil,
                          {:models => []},
                          'function(obj,prev) { 
                                if (_.any(prev.models, function(item){return item == obj.model;}) == false) {
                                  prev.models.push(obj.model);
                                }
                           };')

ap result.to_a  # => [
                #     [0] {"make"=>"Chevy", "models"=>["Corvette", "Camero"]},
                #     [1] {"make"=>"Toyota", "models"=>["Camry"]}
                #    ]