Tame Accidental Complexity with Ruby and MongoMapper

Tame accidental complexity Introduction to NoSQL with MongoMapperGiordano 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

Anatomy of a Rails Applicationview

Anatomy of a Rails Applicationview controller

Anatomy of a Rails Applicationview controller model

Diﬀerent languageshtml+css view controller model

Diﬀerent languageshtml+css oop view controller model

Diﬀerent languageshtml+css oop sql view controller model

Impedance mismatchhtml+css oop sql view controller model

Origin of SqlSQLFrom Wikipedia, the free encyclopediaSQL (...), is a database computer languagedesigned for managing data in relationaldatabase management systems (RDBMS)

We need persistent objects!

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

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

ActiveRecord tries its best

We need something diﬀerent

Persistence

Persistenceclass User include MongoMapper::Documentend

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

Persistenceclass User include MongoMapper::Documentenduser = User.create({ :username => "giordano", :password => "123"})user.saveputs User.all.last.to_mongo

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

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

Built-in TypesArray, Binary, Boolean, Date,Float, Hash, Integer, Nil,ObjectId, Set, String, Time

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

Custom Typesuser = User.newuser.username = "giordano"user.password = "123"user.email = "Giordano.Scalzo@CleanCode.it"user.saveputs User.all.last.to_mongo

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

Embedded Documents

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

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

Embedded Documentsuser.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 }]}

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

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

Documentsp 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

Validations & Callbacksclass User include MongoMapper::Document key :username, String, validates_presence_of :username key :password, String validates_presence_of :passwordend

Validations & Callbacksclass User include MongoMapper::Document key :username, String, :required => true key :password, String, :required => trueend

Validations & Callbacksvalidates_presence_ofvalidates_length_ofvalidates_format_ofvalidates_numericality_ofvalidates_acceptance_ofvalidates_confirmation_ofvalidates_inclusion_ofvalidates_exclusion_of

Validations & Callbacksbefore_save after_savebefore_create after_createbefore_update after_updatebefore_validation after_validationbefore_validation_on_create after_validation_on_createbefore_validation_on_update after_validation_on_updatebefore_destroy after_destroyvalidate_on_create validate_on_updatevalidate

Validations & Callbacksforked in current gem 0.8.6using Rails3 ActiveModel inRails3 branch just merged

What about querying?

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?

What about plugins?Accessible ModifiersAssociations PaginationCaching PersistenceCallbacks ProtectedClone QueryingDirty RailsDocument SafeDynamic Querying SingleEmbeddedDocument CollectionEquality InheritanceIdentityMap ScopesIndexes SerializationInspect TimestampsKeys UserstampsLogger Validations

Itʼs just a beginning

http://mongomapper.com/documentation/

http://mongoid.org/

giordano.scalzo@cleancode.it@giordanoscalzowww.slideshare.net/giordanogithub.com/gscalzo

Tame Accidental Complexity with Ruby and MongoMapper

by giordano scalzo on Feb 25, 2011

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Tame Accidental Complexity with Ruby and MongoMapper Presentation Transcript

http://blog.mikamai.com	11
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