Introduction to Ruby on Rails

Transcription

1 Agnieszka Figiel blog.agnessa.eu Kraków Ruby Users Group May 19th 2007

2 Ruby on Rails "Rails is a full-stack framework for developing database-backed web applications according to the Model-View-Control pattern." - Ruby on Rails official site 2005 David Heinemeier Hansson opinionated software: "it s a very pragmatic, very targeted framework with a strong sense of direction. You might not share its vision, but it undeniably has one." DHH for Linux Journal (

3 Outline Design Principles MVC architecture Agile Development Usability and Success Stories Community and Resources

4 Design Principles MVC architecture Agile Development Usability and Success Stories Community and Resources

5 Model - View - Controller separate data (model) from user interface (view) Model data access and business logic independent of the view and controller View data presentation and user interaction read-only access to the model Controller handling events operating on model and view

6 Database Persistance OR mapping Active Record design pattern migrations incremental schema management multiple db adapters MySQL, PostgreSQL, SQLite, SQL Server, IBM DB2, Informix, Oracle, Firebird/Interbase, LDAP, SybaseASA

7 Full Stack Framework MVC suite built-in webserver default db adapter integrated logger AJAX, web services, test framework plugins

8 Convention over Configuration fixed directory structure everything has its place source files, libs, plugins, database files, documentation etc file naming conventions e.g. camel case class name, underscore file name database naming conventions table names, primary and foreign keys standard configuration files e.g. database connections, environment setting definitions (development, production, test)

9 DRY - Don t Repeat Yourself reusing code e.g. view elements reusing data e.g. no need to declare table field names can be read from the database making each line of code work harder e.g. mini languages for specific domains, like object-relational mapping metaprogramming dynamically created methods

10 Design Principles MVC architecture Agile Development Usability and Success Stories Community and Resources

11 Model - ActiveRecord conventions: name based OR mapping: mice db table -> Mouse class primary key: auto-incremented numeric field called "id" foreign key: "[singular_of_foreign_table_name]_id", e.g. "cat_id" dynamic getters, setters, finders dynamic means the existance of a field in db is enough to manipulate it, e.g. dynamic getter like: mouse.name abstracted db operations - create, update, destroy, find,... possible to use raw sql, but usually unnecessary, e.g.: Mouse.find(:all, :include => {:mouse_holes}, :conditions => "location = shed ", :order => "name", :limit => 10)

12 Model - ActiveRecord support for basic entity relations (1:1, 1:n, n:n) with dynamic accessors backyard_mouse_hole.mice #=> Array of Mouse objects parametrised queries against SQL injection, e.g. find all mice whose name is sth entered by the user: Mouse.find(:all, :conditions => ["name =?", mouse_name) validators: an object won t be saved in db unless it passes all validation rules, e.g. uniqueness of a given field: validates_uniqueness_of :login object life cycle callbacks, e.g. before_create, before_save Single Table Inheritance, polymorphic associations

13 View - ActionView multiple template types oldest and basic: erb (embedded ruby), similar to e.g. jsp remote javascript templates xml templates easy reuse of view elements file inclusion layouts, templates, partials multiple standard "helpers" common html element generators (e.g. form elements, paginators) ridiculously easy AJAX integration prototype, scriptaculous

14 Controller - ActionController all actions grouped logically in controller objects (actions are public methods of the controller class) conventions name based url action mapping e.g. url: myhost.com/mice/show/1 action: show action in MiceController, params: id=1 name based action - template file mapping e.g. action show in MiceController - template file app/views/mice/show.rhtml can be organised in an inheritance hierarchy reduces code duplication and simplifies code action callbacks before_filter, after_filter, around_filter built-in mechanism of url rewrites routes easy access to request data, session, cookies

15 Design Principles MVC architecture Agile Development Usability and Success Stories Community and Resources

16 Rapid Development built-in webserver generators save the fingers scaffold kick-off start plugins, libraries, tons of contributed code

17 Debugging verbose log output breakpoint debugger script/console

18 Testing test database + fixtures unit tests - tests for models functional - tests for controllers integration - tests for workflow testing directly in browser - Selenium

19 Agile Project Heartbeat test coverage - rcov continuous integration iterative db schema control - migrations automated deployment - capistrano

20 Design Principles MVC architecture Agile Development Usability and Success Stories Community and Resources

21 Platform Independence win, lin, mac Apache, Lighttpd, mongrel gem package manager

22 IDEs textmate vim RadRails, Eclipse + RDT, Aptana plugins for Idea, NetBeans SCiTe jedit

23 Scaling it scales a must-see slideshow about scaling twitter (600 req/s!): view caching page caching action caching fragment caching sql caching memcached shared nothing architecture - multiplying application servers

24 Hosting US - a variety of shared hosting offers Poland - poor shared hosting options hosted.pl Root VPS

25 Success Stories several ror powered high traffic sites - community site - music sharing Signals: BaseCamp, BackPack, Ta-Da List, Writeboard, CampFire - storing and sharing files

26 Design Principles MVC architecture Agile Development Usability and Success Stories Community and Resources

27 Books in English: ruby: "Programming Ruby 2nd Edition" (the Pickaxe) Dave Thomas, with Chad Fowler and Andy Hunt "Agile Web Development with Rails" Dave Thomas and David Heinemeier Hansson "Rails Recipes" Chad Fowler many, many more: in Polish: "Programowanie w języku Ruby. Wydanie II" Dave Thomas, Chad Fowler, Andy Hunt "Rails. Przepisy" Chad Fowler "Ruby on Rails. Wprowadzenie" Bruce A. Tate, Curt Hibbs "Ruby on Rails. Ćwiczenia" Michał Sobczak

28 Links main site: PL site: general mailing list: wiki: api: api.rubyonrails.org 74 Quality Ruby on Rails Resources and Tutorials:

29 Events Rails Conf Rails Day local communities & meetings Ruby on Rails workshops: academic presence

30 Questions? pics: holo/seth%20in%20thailand/pages/rail%20tracks.html,