How to use Mongodb with Mongoid gem in Ruby

mongoid_without_rails.rb

# file: mongoid.yml
default:
  sessions:
    production:
      database: foobar
      hosts:
        - localhost:27017


# file: mongoid.rb
require 'mongoid'

Mongoid.load!("mongoid.yml", :production)

class Person
  include Mongoid::Document
  field :first_name, type: String
  field :last_name, type: String
end

p = Person.create(first_name: "Jack", last_name: "Bauer")
puts p.inspect