MongoDB and Ruby on Rails

Discusses choices made for choosing MongoDB and Mongoid as the ORM for Ruby on Rails. Includes examples of developing with Mongoid.

Transcript

1. Using MongoDB with Ruby on Rails presented by Ryan Fischer, Founder of 20spokes
2. What is covered • Why we use MongoDB and Ruby on Rails • Choices made for Object Mapper • Simple to get started!
3. Using MongoDB with Ruby on Rails • Fast in-place updates with atomic modifiers • Ruby on Rails is productive! • Object Mappers available for MongoDB • Mongo Ruby Driver
4. Mobile / Web • Ruby on Rails makes REST easy, making APIs easier. • Render responses as text, JSON, or XML • Geospatial indexing for location based queries. • Location-centric websites and mobile applications.
5. Why we chose MongoDB • Cowrite - collaborative writing web application • Versioning needed • Originally using GridFS • Travel720 - Gift registry web site • Self contained relations can take advantage of embedding documents
6. Mongo Object Mappers for Ruby • MongoMapper • Mongoid • Mongo ODM • MongoModel
7. Why we chose Mongoid • Excellent documentation • Active community • Compatibility with other projects/gems • Similar API to ActiveRecord • Uses ActiveValidation • Mongoid Extras: Caching, Paranoid Documents, Versioning, Timestamping, Composite Keys
8. Compatible Gems with Mongoid • Devise - Authentication solution for Rails based on Warden. Supports Mongoid out of box. • Carrierwave - simple and flexible way to upload files from Ruby Applications. Supports grid_fs. • Geocoder - complete geocoding solution for Rails. Adds geocoding by street or IP address, reverse geocoding, and distance queries. • Mongoid-rspec - RSpec matchers and macros for Mongoid.
9. Getting Started gem "mongoid", "~> 2.3" gem "bson_ext", "~> 1.4" Include in Gem file Run the install for Mongoid rails generate mongoid:config That’s it!
10. mongoid.yml development: host: localhost database: geekbusters_development test: host: localhost database: geekbusters_test production: host: <%= ENV['MONGOID_HOST'] %> port: <%= ENV['MONGOID_PORT'] %> username: <%= ENV['MONGOID_USERNAME'] %> password: <%= ENV['MONGOID_PASSWORD'] %> database: <%= ENV['MONGOID_DATABASE'] %> # slaves: # - host: slave1.local # port: 27018 # - host: slave2.local # port: 27019
11. Developing with MongoDB/Mongoid • Generating models is the same using the console as with ActiveRecord. • rails generate model Team name:string city:string location:array • No migrations needed! • Take advantage of embedded documents in models where applicable for increased performance. • Store large files using GridFS
12. Fields available for Mongoid • Array • BigDecimal (Stored as a String) • Boolean • Date • DateTime • Float • Hash • Integer • Range • String • Symbol • Time
13. Mongoid Document class Team include Mongoid::Document include Mongoid::Timestamps field :name, type: String field :city, type: String field :location, :type => Array validates :name, :city, :presence => true end
14. Persisting in the Controller def create Team.create(:city => "New York", :name => "Giants") end def update @team = Team.find(params[:id]) @team = Team.update_attributes(params[:team]) end
15. Indexing class Team include Mongoid::Document field :name, type: String index :name, unique: true end index( [ [ :name, MONGO::ASCENDING ] [ :city, MONGO::ASCENDING ] ] ) Indexing on multiple fields -
16. Indexing To create indexes in the database use the rake task rake db:mongoid:create_indexes Or configure to autocreate in mongoid.yml (not recommended) defaults: &defaults autocreate_indexes: true
17. Relations in Models • Associations between models can be embedded or referenced • NO JOINS! • Objects that are referenced involve a separate query • Embedded documents can be very efficient with reducing queries to one while managing the size of the document • One to One, One to Many, and Many to Many relations available
18. Relations in Mongoid - Embedded • Embedded Relations - stored inside other documents in the database. class Blog include Mongoid::Document embeds_many :posts end class Post include Mongoid::Document embedded_in :blog end
19. Embedded Posts { "_id" : ObjectId("4e9ba47fcdffba523f000004"), "name" : "Geekbusters Blog", "posts" : [ {"content" : "Slimer is right behind you.", _id" : ObjectId("4e9ba47fcdffba523f000005")} ] }
20. Polymorphic Behavior class Image include Mongoid::Document embeds_many :comments, as: :commentable end class Document include Mongoid::Document embeds_many :comments, as: :commentable end class Comment include Mongoid::Document embedded_in :commentable, polymorphic: true end
21. Relations in Mongoid - Referenced class Blog include Mongoid::Document has_many :posts, dependent: :delete end class Post include Mongoid::Document belongs_to :blog end Referenced Relations - stores reference to a document in another collection, typically an id
22. Many to Many Relationship class Tag include Mongoid::Document has_and_belongs_to_many :posts end class Post include Mongoid::Document has_and_belongs_to_many :tags end
23. Querying • Queries are of type Criteria, which is a chainable and lazily evaluated wrapper to a MongoDB dynamic query. • Chainable queries include: all_in all_of also_in and any_of asc desc distinct excludes includes limit near not_in only order_by skip where without
24. Query Examples Team.near(location: [20.70, 38.15]).limit(20) Team.any_in(names: ["Giants", "Bears", "Lions"]) Team.find_or_create_by(name: "Giants") Team.where(name: "Cowboys").destroy_all
25. Versioning with Mongoid • Embeds a version of the object on each save. • Can skip versioning and also set the max versions. • Add to model - include Mongoid::Versioning
26. Versioning Example {"_id" : ObjectId("4e9ba7fdcdffba52d6000004"), "content" : "Impossible. I am too loud to fall asleep to.", "created_at" : ISODate("2011-10-17T03:58:53Z"), "title" : "Impossible to sleep to - this guy.", "updated_at" : ISODate("2011-10-17T03:58:53Z"), "version" : 3, "versions" : [ {"title" : "Who is asleep?", "content" : "Wake up the guy next to you if they are asleep. Thanks.", "version" : 1, "created_at" : ISODate("2011-10-17T03:58:53Z")}, {"title" : "Who is asleep?", "content" : "Impossible. I am too loud to fall asleep to.", "created_at" : ISODate("2011-10-17T03:58:53Z"), "version" : 2 } ] }
27. And More • Identity Map • Callbacks • Scopes • Dirty Tracking
28. Testing Rails with MongoDB • RSpec-Mongoid provides test matchers • RSpec does not refresh the database with each test run. • Database Cleaner to the rescue. It be setup to truncate a database before running tests. Add below after installing the DatabaseCleaner Gem. config.before(:suite) do DatabaseCleaner.strategy = :truncation DatabaseCleaner.orm = "mongoid" end
29. Hosting Options • Heroku is a widely used cloud hosting for Ruby on Rails • MongoHQ and MongoLab both have add on options • Options and pricing are similar
30. Thanks!! Email: ryan.fischer@20spokes.com Twitter: @ryanfischer20 Check out Geekbusters on Github