Tenacity

Tenacityhttps://github.com/jwood/tenacity ChicagoDB June 20, 2011

Polyglot Persistence is Great! Managing relationships...not so much

class Car include MongoMapper::Document def wheels Wheel.where(:car_id => self.id) endendclass Wheel < ActiveRecord::Base # car_id deﬁned on the table def car Car.ﬁnd(self.car_id) endend

Problems• Lots of boilerplate code• Bogus values can be stored in car_id• What happens if the Car is deleted?• Objects fetched from the database each time• Adding new wheels is awkward

Introducing Tenacity• Heavily based on ActiveRecord::Associations• Support for has one, belongs to, and has many relationships• Adds foreign key like behavior• Can “clean up” when objects are deleted• Related objects are fetched from the database once and then cached

Introducing Tenacity• Easily work with collections of associated objects• Polymorphic associations• Read only associations• Support for a wide array of popular Ruby ORM/ODM libraries

class Car include MongoMapper::Document def wheels Wheel.where(:car_id => self.id) endendclass Wheel < ActiveRecord::Base # car_id deﬁned on the table def car Car.ﬁnd(self.car_id) endend

class Car include MongoMapper::Document include Tenacity t_has_many :wheelsendclass Wheel < ActiveRecord::Base include Tenacity t_belongs_to :carend

class Car include MongoMapper::Document include Tenacity t_has_many :wheels t_has_one :dashboardendclass Wheel < ActiveRecord::Base include Tenacity t_belongs_to :carendclass Dashboard < CouchRest::Model::Base include Tenacity use_database MY_DATABASE t_belongs_to :carend

car = Car.create# Set the related objectdashboard = Dashboard.createcar.dashboard = dashboardcar.save# Fetch related object from the respective databasecar.dashboard# Fetch related object idcar.dashboard.car_id

# Set related objectswheel_1 = Wheel.createwheel_2 = Wheel.createwheel_3 = Wheel.createwheels = [wheel_1, wheel_2, wheel_3]car.wheels = wheelscar.savewheel_1.car_id # car.id# Fetch array of related objects from the respective databasecar.wheels # [wheel_1, wheel_2, wheel_3]# Fetch ids of related objects from the databasecar.wheel_ids # [wheel_1.id, wheel_2.id, wheel_3.id]# Add a related object to the collectionnew_wheel = Wheel.createcar.wheels << new_wheelcar.savecar.wheels # [wheel_1, wheel_2, wheel_3, new_wheel]

How Does It Work?• Extends supported libraries with a common set of methods• Tenacity uses these methods to work with the objects in a generic fashion• Methods are added to the model class to interact with the relationship• ORM/ODM callback functionality is used to trigger Tenacity to save associated objects, cleanup associations, etc

Supported Libraries• ActiveRecord • MongoMapper (2.x and 3.x) • Mongoid• CouchRest • Ripple (CouchModel and ExtendedDocument) • Sequel• DataMapper • Toystore

What’s On Deck?• Add support for many to many associations• Add support for build and create methods • Author.posts.build• Improve performance• Continue adding support for additional ORM/ ODM libraries

Thanks!john@johnpwood.net @johnpwood

Tenacity

by John Wood on Jun 21, 2011

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