tame accidental complexity with ruby and mongomapper

Tame accidental complexityIntroduction to NoSQL with MongoMapper

Giordano Scalzo

I’m not here to talk about performance

I’m not here to talk about scalability

but I’m here to talk about simplicity

Rails has been a first step

Anatomy of a Rails Application


view


view controller


modelview controller

Different languages


html+css

Different languages


html+css oop

Different languages


html+css oop sql

Impedance mismatch


html+css oop sql

Origin of Sql

SQL (...), is a database computer language designed for managing data in relational database management systems (RDBMS)

SQLFrom Wikipedia, the free encyclopedia

http://en.wikipedia.org/wiki/Database


http://en.wikipedia.org/wiki/Data

http://en.wikipedia.org/wiki/Data

http://en.wikipedia.org/wiki/Relational_database_management_systems




Origin of Sql

SQL (...), is a database computer language designed for managing data in relational database management systems (RDBMS)

SQLFrom Wikipedia, the free encyclopedia















We need persistent objects!


class User def initialize(username, password) @username = username @password = password endend


{ username: "giordano", password: "123"}

ActiveRecord tries its best

We need something different

Persistence

Persistence

class User include MongoMapper::Documentend

Persistence


user = User.create({ :username => "giordano", :password => "123"})user.save

Persistence


user = User.create({ :username => "giordano", :password => "123"})user.save

puts User.all.last.to_mongo

Persistence

{ "_id"=>BSON::ObjectId('4d643a274d8ff683dd000001'), "username"=>"giordano", "password"=>"123"}

Types

class User include MongoMapper::Document key :username, String key :password , Stringend

Built-in Types

Array, Binary, Boolean, Date, Float, Hash, Integer, Nil, ObjectId, Set, String, Time

Custom Types

class DowncasedString def self.to_mongo(value) value.nil? ? nil : value.to_s.downcase end def self.from_mongo(value) value.nil? ? nil : value.to_s.downcase endend

Custom Types

class User include MongoMapper::Document key :username, String key :password , String key :email, DowncasedStringend

Custom Types

user = User.newuser.username = "giordano"user.password = "123"user.email = "[email protected]"

user.save

puts User.all.last.to_mongo

mailto:[email protected]


Custom Types

{ "_id"=>BSON::ObjectId('4d6442d94d8ff684d3000001'), "username"=>"giordano", "password"=>"123", "email"=>"[email protected]"}



Embedded Documents

Embedded Documents

class Task include MongoMapper::EmbeddedDocument key :description, String key :pomodori, Integer key :is_done, Booleanend

Embedded Documents

class User include MongoMapper::Document key :username, String key :password , String key :email, DowncasedString many :tasksend

Embedded Documents

user.tasks << Task.new({ description: 'refactor server', pomodori: 8, is_done: false})

user.tasks << Task.new({ description: 'timer sound', pomodori: 2, is_done: false})

Embedded Documents

{"_id"=>BSON::ObjectId('4d6575e84d8ff692e6000001'), "username"=>"giordano", "password"=>"123", "email"=>"[email protected]", "tasks"=>[{ "_id"=>BSON::ObjectId('4d6575e84d8ff692e6000002'), "description"=>"refactor server", "pomodori"=>8, "is_done"=>false }, { "_id"=>BSON::ObjectId('4d6575e84d8ff692e6000003'), "description"=>"timer sound", "pomodori"=>2, "is_done"=>false }]}



Documents

class Task include MongoMapper::Document key :description, String key :pomodori, Integer key :is_done, Booleanend

Documents

p User.all.last.to_mongo

{ "_id"=>BSON::ObjectId('4d657e924d8ff6949c000001'), "username"=>"giordano", "password"=>"123", "email"=>"[email protected]"}



Documents

p User.all.last.tasks

[#<Task _id: BSON::ObjectId('4d65822b4d8ff69542000002'), description: "refactor server", pomodori: 8, is_done: false, user_id: BSON::ObjectId('4d65822b4d8ff69542000001') >, #<Task _id: BSON::ObjectId('4d65822b4d8ff69542000003'), description: "timer sound", pomodori: 2, is_done: false, user_id: BSON::ObjectId('4d65822b4d8ff69542000001') >]

Validations & Callbacks


class User include MongoMapper::Document key :username, String, validates_presence_of :username key :password, String validates_presence_of :passwordend


class User include MongoMapper::Document key :username, String, :required => true key :password, String, :required => trueend


validates_presence_ofvalidates_length_ofvalidates_format_ofvalidates_numericality_ofvalidates_acceptance_ofvalidates_confirmation_ofvalidates_inclusion_ofvalidates_exclusion_of


before_save after_save before_create after_create before_update after_update before_validation after_validation before_validation_on_create after_validation_on_create before_validation_on_update after_validation_on_update before_destroy after_destroy validate_on_create validate_on_update validate


forked in current gem 0.8.6using Rails3 ActiveModel in Rails3 branch just merged

What about querying?


Plucky: ActiveRecord-like language

query = User.where(:last_name.exists => true, :created_at.gte => from_date, :created_at.lt => Time.now) .skip(0).limit(5)

query.all



query = User.where(:last_name.exists => true, :created_at.gte => from_date, :created_at.lt => Time.now) .skip(0).limit(5)

#<Plucky::Query created_at: { "$gte"=>"1", "$lt"=>2011-02-24 10:54:36 UTC}, last_name: {"$exists"=>true}, limit: 5, skip: 0>



query = User.where(:last_name.exists => true) .where(:created_at.gte => from_date) .where(:created_at.lt => Time.now) .skip(0).limit(5)

#<Plucky::Query created_at: { "$gte"=>"1", "$lt"=>2011-02-24 10:54:36 UTC}, last_name: {"$exists"=>true}, limit: 5, skip: 0>

What about plugins?

What about plugins?AccessibleAssociationsCachingCallbacksCloneDirtyDocumentDynamic QueryingEmbeddedDocumentEqualityIdentityMapIndexesInspectKeysLogger

ModifiersPaginationPersistenceProtectedQueryingRailsSafeSingle Collection InheritanceScopesSerializationTimestampsUserstampsValidations

Itʼs just a beginning

http://mongomapper.com/documentation/



http://mongoid.org/

http://mongoid.org/

http://mongoid.org/

@giordanoscalzo

www.slideshare.net/giordano

github.com/gscalzo

[email protected]

