An example using the Tenacity gem

tenacity_example.rb

class Car
  include MongoMapper::Document
  include Tenacity

  t_has_many :wheels
  t_has_one  :dashboard
end

class Wheel < ActiveRecord::Base
  include Tenacity

  t_belongs_to :car
end

class Dashboard < CouchRest::ExtendedDocument
  include Tenacity
  use_database MY_COUCHDB_DATABASE

  t_belongs_to :car
end

car = Car.create

# Set the related object
dashboard = Dashboard.create({})
car.dashboard = dashboard
car.save

# Fetch related object from the respective database
car.dashboard

# Fetch related object id
car.dashboard.car_id

# Set related objects
wheel_1 = Wheel.create
wheel_2 = Wheel.create
wheel_3 = Wheel.create
wheels = [wheel_1, wheel_2, wheel_3]
car.wheels = wheels
car.save

wheel_1.car_id    # car.id

# Fetch array of related objects from the respective database
car.wheels        # [wheel_1, wheel_2, wheel_3]

# Fetch ids of related objects from the database
car.wheel_ids     # [wheel_1.id, wheel_2.id, wheel_3.id]

# Add a related object to the collection
new_wheel = Wheel.create
car.wheels << new_wheel
car.save
car.wheels        # [wheel_1, wheel_2, wheel_3, new_wheel]