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Ruby on rails for beginers
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Ruby on rails for beginers



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  • 1. Presentation to Siltek Software Solutions (I) Pvt. Ltd.
  • 2. Why does RoR interest us?  Learn “new” concepts and terms.  Look at “new” architecture.  Find out what is good and what is dubious.  May well come across RoR or a Rails-like framework in near future.  May want to learn an object-oriented language relatively painlessly.  RoR is easy to install, learn and use. You might want to try it out for yourself!
  • 3. Creator of Ruby  Creator of Ruby  Yukihiro Matsumoto aka Matz  Birthday: 24 February 1993  Originated in Japan and Rapidly Gaining Mindshare in US and Europe.
  • 4. Presentation Agenda  Brief overview of Ruby  Rails Demonstration  Description of Rails framework  Questions and Answers
  • 5. Why Ruby?  Write more understandable code in less lines  Free (Very open license)  Extensible
  • 6. What is Ruby? Dynamic, high level, interpreted, pure object-orientated language. “Ruby is designed to make programmers happy” Yukihiro Matsumoto aka Matz
  • 7. What is Ruby?  Ruby is a pure object-oriented programming language with a super clean syntax that makes programming elegant and fun.  In Ruby, everything is an object  Ruby is an interpreted scripting language, just like Perl, Python and PHP.  Ruby successfully combines Smalltalk's conceptual elegance, Python's ease of use and learning and Perl's pragmatism.  Ruby is a metaprogramming language. Metaprogramming is a means of writing software programs that write or manipulate other programs thereby making coding faster and more reliable.
  • 8. Ruby is Truly Object-Oriented  All classes derived from Object including Class (like Java) but there are no primitives (not like Java at all)  Ruby uses single-inheritance  Mixins give you the power of multiple inheritance without the headaches  Modules allow addition of behaviors to a class  Reflection is built in along with lots of other highly dynamic metadata features  Things like ‘=‘ and ‘+’ that you might think are operators are actually methods (like Smalltalk)
  • 9. Dynamic Programming  Duck Typing Based on signatures, not class inheritance  Dynamic Dispatch A key concept of OOP: methods are actually messages that are sent to an object instance  Dynamic Behavior  Reflection  Scope Reopening (Kind of like AOP)  Eval  Breakpoint debugger
  • 10. What about Ruby on Rails?
  • 11. Terms and Concepts  MVC (Model-View-Controller)  Duck Typing  DRY (Don’t Repeat Yourself)  Convention Over Configuration  Scaffolding  Migrations  Validations  Associations  Mailers
  • 12. Directory Layout Rails applications have a common directory structure /app - the MVC core /controllers /helpers - provides extra functionality for views /models /views/nameofcontroller - templates for controller actions
  • 13. Directory Layout /components - will be deprecated /config - database, route and environment configuration /db - database schema and migrations /lib - functions that don’t map to MVC /log /public - static web resources (html, css, javascript etc.) /script - rails utilities /test - tests and fixtures /tmp /vendor - 3rd party plugins
  • 14. Rails Directory Structure
  • 15. MVC Architecture
  • 16. The Obligatory Architecture Slide
  • 17. 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
  • 18. Model – Active Record  Object Relational Mapping  “ActiveRecord”  Less Database “glue” Code  Logging for Performance Checking
  • 19. Model : Rules  Table Names  Plurals  Attribute Names  id for primary key in table  table_id for foreign key in other table
  • 20. View – Action View  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)  easy AJAX integration
  • 21. Controller : ActionController  Method name matches view folder  users_controller.rb works for /views/users/***.rhtml  called “actions”  all view’s methods will sit there  Ability to  CRUD  Flash  Redirect
  • 22. Database Persistence  OR mapping  Active Record design pattern  migrations  incremental schema management  multiple db adapters  MySQL, PostgreSQL, SQLite, SQL Server, IBM DB2, Informix, Oracle
  • 23. Duck Typing in Ruby  Objects are dynamic, and their types are determined at runtime  The type of a Ruby object is much less important than it’s capabilities  If a Ruby object walks like a duck and talks like a duck, then it can be treated as a duck
  • 24. 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)
  • 25. 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  object-relational mapping  metaprogramming  dynamically created methods
  • 26. Rails Environment Modes  Rails runs in different modes, depending on the parameters given to the server on startup. Each mode defaults to it’s own database schema Development (verbose logging and error messages) Test Production
  • 27. Web Servers  Lighttpd  Mongrel  WEBrick  Apache
  • 28. RoR Databases  Mysql  Oracle  Postgre Sql  SqlLite
  • 29. Scaffolding  Rails can generate all the basic CRUD operations for simple models via scaffolding.  Scaffolding is temporary way to get applications wired quickly.  ruby script/generate scaffold_resource bookmark url:string title:string
  • 30. Migrations  Rails uses migrations to version the database.  Rails tries to minimize SQL at every opportunity  Migrations are automatically created whenever you generate a new model  Migration files are located in db/migrations  The version number is stored in a table called schema_info
  • 31. Running the Migration  Rake is the general purpose build tool for rails, much like make, or ant. It has many functions, one of which is to control migrations.  rake db:migrate  Now the table has been created
  • 32. Validations  Rails has a number of validation helpers that can be added to the model. class Bookmark < ActiveRecord::Base validates_presence_of :url, :title end
  • 33. Validations  validates_presence_of  validates_length_of  validates_acceptance_of  validates_confirmation_of  validates_uniqueness_of  validates_format_of  validates_numericality_of  validates_inclusion_in  validates_exclusion_of  validates_associated :relation
  • 34. Associations  Rails uses associations to build relationships between tables  Associations are independent of database foreign key constraints
  • 35. Types of Associations  has_one  belongs_to  has_many  has_and_belongs_to_many  has_many :model1, :through => :model2
  • 36. Mailers  Action Mailer allows you to send emails from your application using a mailer model and views. So, in Rails, emails are used by creating models that inherit from ActionMailer::Base that live alongside other models in app/models. Those models have associated views that appear alongside controller views in app/views.
  • 37. Rake  Ruby’s Build System  Familiar to Ant users  Your build file is a written in Ruby  Basic build script provided with Rails project
  • 38. Recommended Rails reading  Simply Rails 2.0  Great for beginners  Agile Web Development with Rails  A little bit more advanced
  • 39. Resources  Ruby on Rails: Talk (Google Group)   Railscasts (free Ruby on Rails screencasts)   Peep Code (paid Rails-related screencasts)   Phusion Passenger (easy deployment module)   Agile Web Development (plugin central) 
  • 40. Who uses Ruby on Rails?
  • 41. References     weblog.html   