Tame Accidental Complexity with Ruby and MongoMapper

Tame accidental complexity Introduction 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

Anatomy of a Rails Application

Anatomy of a Rails Application view

Anatomy of a Rails Application view controller

Anatomy of a Rails Application view controller model

Diﬀerent languages html+css view controller model

Diﬀerent languages html+css oop view controller model

Diﬀerent languages html+css oop sql view controller model

Impedance mismatch html+css oop sql view controller model

Origin of Sql SQL From Wikipedia, the free encyclopedia SQL (...), is a database computer language designed for managing data in relational database management systems (RDBMS)

We need persistent objects! class User def initialize(username, password) @username = username @password = password end end

We need persistent objects! { username: "giordano", password: "123" }

Persistence class User include MongoMapper::Document end

Persistence class User include MongoMapper::Document end user = User.create({ :username => "giordano", :password => "123" }) user.save

Persistence class User include MongoMapper::Document end 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 , String end

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 end end

Custom Types class User include MongoMapper::Document key :username, String key :password , String key :email, DowncasedString end

Custom Types user = User.new user.username = "giordano" user.password = "123" user.email = "Giordano.Scalzo@CleanCode.it" user.save puts User.all.last.to_mongo

Custom Types { "_id"=>BSON::ObjectId('4d6442d94d8ff684d3000001'), "username"=>"giordano", "password"=>"123", "email"=>"giordano.scalzo@cleancode.it" }

Embedded Documents class Task include MongoMapper::EmbeddedDocument key :description, String key :pomodori, Integer key :is_done, Boolean end

Embedded Documents class User include MongoMapper::Document key :username, String key :password , String key :email, DowncasedString many :tasks end

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"=>"giordano.scalzo@cleancode.it", "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, Boolean end

Documents p User.all.last.to_mongo { "_id"=>BSON::ObjectId('4d657e924d8ff6949c000001'), "username"=>"giordano", "password"=>"123", "email"=>"giordano.scalzo@cleancode.it" }

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 :password end

Validations & Callbacks class User include MongoMapper::Document key :username, String, :required => true key :password, String, :required => true end

Validations & Callbacks validates_presence_of validates_length_of validates_format_of validates_numericality_of validates_acceptance_of validates_confirmation_of validates_inclusion_of validates_exclusion_of

Validations & Callbacks 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

Validations & Callbacks forked in current gem 0.8.6 using Rails3 ActiveModel in Rails3 branch just merged

What about querying? query = User.where(:last_name.exists => true, :created_at.gte => from_date, :created_at.lt => Time.now) Plucky: ActiveRecord-like language .skip(0).limit(5) query.all

What about querying? query = User.where(:last_name.exists => true, :created_at.gte => from_date, :created_at.lt => Time.now) Plucky: ActiveRecord-like language .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 querying? query = User.where(:last_name.exists => true) .where(:created_at.gte => from_date) .where(:created_at.lt => Time.now) Plucky: ActiveRecord-like language .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? Accessible Modifiers Associations Pagination Caching Persistence Callbacks Protected Clone Querying Dirty Rails Document Safe Dynamic Querying Single EmbeddedDocument Collection Equality Inheritance IdentityMap Scopes Indexes Serialization Inspect Timestamps Keys Userstamps Logger Validations

http://mongomapper.com/documentation/

giordano.scalzo@cleancode.it @giordanoscalzo www.slideshare.net/giordano github.com/gscalzo

Tame Accidental Complexity with Ruby and MongoMapper

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