MongoDB is a document-oriented database that offers dynamic queries, fast updates, and schemaless design. It can scale horizontally and is suitable for most websites and caching applications. MongoDB uses MongoMapper for object-relational mapping with Ruby, allowing developers to define schemas and relationships between documents. Documents can be embedded within other documents to reduce joins and optimize performance.

1. MONGODB AND RUBY
Persisting dynamic data with MongoMapper

3. MONGODB
• humongous • auto-sharding
• Speed!!! • replication and fail-over
• document-oriented storage • GridFS
(BSON)
• MapReduce
• dynamic queries
• Schemaless
• fast, in-place updates

4. USE IT FOR..
• (most) Websites
• Caching
• Scalabilty

5. SKIP IT FOR..
• Transactions
• Lots of joins
• Fixed datasets (science,...)

6. START USING IT
• MongoDB in google: www.mongodb.org - Quickstart
• make a directory
• download mongodb
• unpack

7. START USING IT

8. START USING IT

9. QUERYING
> db.fosdem.save({talk: "MongoDB", presenter: "Bernard"})
> db.fosdem.find()
{
"_id" : ObjectId("4b681a1ecf1bcfea49f4b2ae"),
"talk" : "MongoDB",
"presenter" : "Bernard"
}

10. MORE QUERYING
> db.fosdem.find({presenter: "Bernard")
{
"_id" : ObjectId("4b681a1ecf1bcfea49f4b2ae"),
"talk" : "MongoDB",
"presenter" : "Bernard"
}

11. MORE QUERYING

13. gem install mongo_mapper
gem install mongo_ext

14. require 'mongo_mapper'
MongoMapper.database = ‘fosdem’

15. class Presenter
include MongoMapper::Document
end

16. class Presenter
include MongoMapper::Document
key :name, String
key :confirmed, Boolean
key :keywords, Array
key :presentation, Presentation
end

17. presenter = Presenter.new({
:name => “Bernard”,
:confirmed => true,
:keywords => [“Openminds”, “geek”]
})
presenter.save
presenter.destroy

18. ACTIVERECORD, ANYONE?

19. MONGOMAPPER HAS
• validates_*
• before_save / after_update / ...
• has_many / belongs_to
• timestamps!

20. CUSTOM DATATYPES
class Keywords class Presenter
def initialize(array) include MongoMapper::Document
@words = array key :keywords, Keywords
end end
def to_a
@words
end
class << self
def to_mongo(value)
value.is_a?(Keyword) ? keyword.to_a : value
end
def from_mongo(value)
value ? self.new(value) : nil
end
end
end

21. EMBEDDED DOCUMENT
include MongoMapper::EmbeddedDocument

22. DYNAMIC?

23. INHERITANCE
class Page class BlogPost < Page
key :permalink, String key :content, String
key :title, String has_many :comments
end end
class Redirect < Page
key :destination, String
end

24. MODULAR
module Authentication
def self.included(base)
base.key :password, String
base.key :salt, String
base.key :login, String
end
end
class Person
include MongoMapper::Document
include Authentication
end

25. MULTISITE WEBSHOP
EXAMPLE
per instance data gathering

26. ORDERS AS A DOCUMENT
class Order
include MongoMapper::Document
key :order_id, String
class << self
def for_site(site)
klass = Class.new(self)
klass.order_fields = site.order_fields
Object.const_set("OrderForSite#{site.id}", klass)
klass
end
def order_fields=(fields)
fields.each do |field|
key field, String
end
end
end
end

27. ORDERS: MONGOMAPPER
class Order
include MongoMapper::Document
key :order_id, String

28. ORDER: CLASS FOR A SPECIFIC
SITE
def for_site(site)
klass = Class.new(self)
klass.order_fields = site.order_fields
Object.const_set("OrderForSite#{site.id}", klass)
klass
end

29. DYNAMIC DOCUMENT
BUILDING
def order_fields=(fields)
fields.each do |field|
key field, String
end
end

30. PER USER
class Order
include MongoMapper::Document
key :order_id, String
class << self
def for_site(site)
klass = Class.new(self)
klass.order_fields = site.order_fields
Object.const_set("OrderForSite#{site.id}", klass)
klass
end
def order_fields=(fields)
fields.each do |field|
key field, String
end
end
end
end

31. SITE
• Can be a Mongo-document
• Can be an ActiveRecord object
• Can be a (Rails 3) ActiveModel object (REST?)
• Has to “respond_to? :id” and “respond_to? :order_fields”

32. TRY IT OUT
current_site.order_fields
#=> [“field1”, “field2”]
@order = Order.for_site(current_site).new
#=> #<OrderForSite2172858380 field1: nil, field2: nil,
order_id: nil>

33. Q&A

34. 1
2
3
4
5
6
7
• Bernard Grymonpon
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
• Openminds BVBA
• Hosting & Rails-shop ribbit
• @wonko_be - @openminds_be
Top sites deserve
maximum uptime
openminds.be
tailored hosting solutions