Mongoid is an object document mapper (ODM) for MongoDB that allows developers to work with MongoDB documents as objects. Some key features of Mongoid include defining document schemas with fields and associations like references and embeds, validation support, indexing, integration with Rails caching and authentication frameworks like Devise, and dropping down to the lower-level MongoDB driver when needed for performance. Mongoid aims to provide an everyday ORM solution for MongoDB along with features for testing, searching, and file uploads.

1. Mongoid in the
Real World
Toronto Ruby Brigade Kevin Faustino
December 14, 2010 @kfaustino
http://adventuresincoding.com

2. Thanks to our sponsors

3. What is Mongoid?

4. Object Document
Mapper

6. Using Mongoid
Everyday Mongoid
Integrations

7. class Post
end

8. class Post
include Mongoid::Document
end

9. Types

10. class Post
include Mongoid::Document
include Mongoid::Timestamps
field :title
field :content
field :published_on, :type => DateTime
field :slug
end

11. Valid Types
Array, BigDecimal, Boolean, Date, DateTime, Float, Hash,
Integer, String, Symbol, Time

12. Associations

13. class Person
include Mongoid::Document
field :first_name
field :last_name
embeds_one :address
end
class Address
include Mongoid::Document
field :street
field :city
embedded_in :person, :inverse_of => :address
end

14. {
"_id" : ObjectId("4d06eaa46c50a1031a000001"),
"address" : {
"_id" : ObjectId("4d06eade6c50a1031a000002"),
"street" : "123 Liberty St.",
"city" : "Toronto"
},
"first_name" : "Kevin",
"last_name" : "Faustino"
}

15. class Blog
include Mongoid::Document
references_many :posts
end
class Post
include Mongoid::Document
referenced_in :blog
end

16. {
"_id" : ObjectId("4c9f54866c50a10a75000003"),
"blog_id" : ObjectId("4ca531c46c50a12d1b000002"),
"content" : "What is Faraday? ...",
"featured_image_filename" : "faraday.jpg",
"slug" : "building-modular-http-client-code-with-
faraday",
"title" : "Building modular HTTP client code with
Faraday",
}

17. Validations

18. ActiveModel Validators + More
validates_acceptance_of
validates_associated
validates_confirmation_of
validates_exclusion_of
validates_format_of
validates_inclusion_of
validates_length_of
validates_numericality_of
validates_presence_of
validates_uniqueness_of

19. Indexing

20. Defining Indexes
# unique
index :ssn, :unique => true
# Compound indexes
index([
[ :first_name, Mongo::ASCENDING ],
[ :last_name, Mongo::ASCENDING ]
])
# Foreign Key indexes
referenced_in :post, :inverse_of
=> :comments, :index => true

21. Using Mongoid
Everyday Mongoid
Integrations

22. Document Limit

23. 4 MB

25. Testing

26. RSpec Integration
# in spec/spec_helper.rb
RSpec.configure do |config|
config.mock_with :rspec
config.before :each do
Mongoid.master.collections.select {|c| c.name !~ /
system/ }.each(&:drop)
end
end

27. Shoulda Matchers?

28. Use Remarkable
# in spec/spec_helper.rb
require 'remarkable/active_model'
require 'remarkable/mongoid'

29. Mongoid Matchers
have_field
reference_one
reference_many
be_referenced_in
embed_one
embed_many
be_embedded_in
validate_uniqueness_of
validate_association
All ActiveModel validations from Remarkable::ActiveModel

30. Cucumber Integration
# features/support/hooks.rb
Before do |scenario|
Mongoid.master.collections.select {|c| c.name !~ /system/ }.each
(&:drop)
end

31. Factory Girl

32. Works out of the box
FactoryGirl.define do
factory :post do
title 'My first blog post'
author 'Kevin Faustino'
content 'Hello World'
end
end

33. Factories with Cucumber
# features/support/env.rb
require 'factory_girl'
require 'factory_girl/step_definitions'

34. Monkey Patched Step Definition
# features/step_definitions/mongoid_steps.rb
Given /^an? (.+) exists with an? (.+) of "([^"]*)"$/
do |model, field, value|
factory_name = model.gsub(' ', '_')
Factory factory_name, field => value
end

35. Example Feature Usage
Given the following posts exist:
| title | excerpt |
| 10 greatest Batman Villians | We countdown ... |
| The Death of Batman | Batman falls ... |

36. Caching in Rails

37. Create a Cache-Key
module Cacheable
def cache_key
if new_record?
"#{collection_name}/#{id}/new"
elsif respond_to?(:updated_at)
"#{collection_name}/#{id}-#{updated_at.to_i}"
else
"#{collection_name}/#{id}"
end
end
end

38. Safe Operations

39. post = Post.safely(:w => 2).create(
:title => 'We will receive verification'
)
post.safely(:w => 2).destroy

40. Safely Options
:w - A client can block until a write
operation has been replicated to N servers
:fsync - force the database to fsync all files
before returning

41. Enslave

42. Query from your Slaves
# Query specific
Post.where(:title => 'Toronto Ruby').enslave
# Document specific
class Post
include Mongoid::Document
enslave
end

43. Dropping Down

44. When you need more
performance, drop down
to the driver

45. collection = mongo-ruby-driver
# Add a post id only if it does not already exist on
# the set
collection.update({'_id' => id}, {'$addToSet' =>
{'post_ids' => post.id}})

46. Using Mongoid
Everyday Mongoid
Integrations

47. Full Text-Search

48. Use Solr
@solr = RSolr.connect :url => "http://127.0.0.1:8983/solr"
@solr.add( {
:id => post.id,
:text => post.content,
:published_on => post.published_on.strftime("%Y-%m-%dT%H:%M:
00Z")
}, { :add_attributes => { :commitWithin => 10000 } })

49. Photo Uploads

50. Not with paperclip!
X

52. Agnostic

53. Document Example
class Post
include Mongoid::Document
include Mongoid::Timestamps
field :title
field :author
field :content
field :slug
referenced_in :blog
mount_uploader :featured_image, ImageUploader
end

54. Authentication

55. Use Devise
class User
include Mongoid::Document
devise :database_authenticatable,
:rememberable,
:trackable,
:validatable
end

56. Coming Soon

57. Many to Many support
without dropping down
to the driver

58. Thank you!