RUBY ON RAILS

AN INTRODUCTION

ABOUT ME

• Constantine Nicolaou

• Software Developer

•Works for Mekentosj B.V. (UK)

• twitter : @cnicolaou

• github: cnicolaou

ABOUT RUBY

• Creator: Yukihiro Matsumoto (Matz)

• Released in 1995

• Open Source

• Remained relatively underused outside of Japan until Rails brought it to prominence (2003)

• Cross platform (OS X, Linux and Windows)

• RubyGems: package manager for Ruby (gem install rails)

ABOUT RAILS(ELEVATOR PITCH)

• Open Source web framework created by David Heinemeier Hansson (DHH) in 2003(get it from github.com/rails/rails)

• Developed with happiness and productivity of developers in mind

• Beautiful and readable syntax (thanks to Ruby)

• Favours convention over configuration(plural tables names, singular model names)

• Don’t Repeat Yourself (DRY)

BEAUTIFUL SYNTAX? REALLY?RAILS CONTROLLER CLASS

MORE ON RUBY

• Everything is an Object

•Dynamic (no type declarations)

•No brackets for simple method calls

• Last statement of a method is automatically returned(18:09) costa:~/dev/apps$ irbree-1.8.7-2011.03 :001 > def add(number1, number2); number1 +number2; end;ree-1.8.7-2011.03 :002 > add(1, 5)=> 6

RUBY DATA STRUCTURES

data type literal description

integer 1

range 1..5

string ‘rails’

float 1.0 floating-point representation

symbol :rails string for identifying purpose

array [‘a’, ‘b’] list of objects, fixed order

hash {:a=>1} Collection of key, value pairs

CODE EXAMPLES

simple loop in Ruby

simple loop in PHP

loop in Java

simplest loop so far?

SO, WHY RAILS?

• Easy, fast and fun way to develop web applications

• MVC (Model-View-Controller) architectural pattern

• Predefined application structure

• Rails was built with testing support in mind (test folder exists by default in the application structure)

• Different environments within the same application (database.yml)

• Active community and lots of resources to learn from

ALSO, BIG NAMESRUBYONRAILS.ORG/APPLICATIONS

RAILS MVCHOW DOES IT WORK?

ACTIVERECORD(OBJECT-RELATION MAPPING (ORM) PUT ON RAILS)

•ORM pattern:An object that wraps a row in a database table... and adds domain logic on that data (Martin Fowler)

• Ruby classes that are located under app/models

•One database table maps to one Ruby class

• Attributes are columns

• Associations between objects(A user has many blog posts)

SHOW US SOME CODE

...switching to terminal

ACTIVERECORD - 2

• Associations (has_one, has_many, belongs_to, has_and_belongs_to_many)

• Validations: rules in models on objectsvalidates_presence_of :name

• Callbacks: before_save, before_update, after_create

ACTIONVIEW

• Embedding Ruby in HTML (ERb template engine)<h1>People</h1><ul> <% @people.each do |person| -%> <li><%= person.first_name %></li> <% end -%></ul>

• Forms:Form Helpers / to HTML / to params / to ActiveRecord then validate attributes and save

BACK TO PAPERSPAPERS: SEARCH, READ, CITE, SHARE

AVOIDING THIS

LIVFE IS PAPERS COLLABORATIVE SOLUTION

Your Papers life, live.Papers Livfe

PAPERS LIVFE

•Organise and share papers using Livfe Collections

•Micro comments, reviews and ratings on papers

• Send and receive papers recommendations

• Adds collaboration to existing workflow

PAPERS LIVFE(UNDER THE HOOD)

• Based on Ruby on Rails

• Private APIs to Papers apps (Mac, iOS)

•Different representational formats based on request types

• Recommend papers to users based on criteria(for example: keywords or field of interest or job title)

EXAMPLE OF AN API

Consuming the API (with cURL)curl -X GET -H "Accept: text/xml" http://username:password@livfe.net/api/v1.2/collections/

ONE MORE THING

“Your time is limited, so don’t waste it living someone else’s life… Stay hungry. Stay foolish.”Steve Jobs, Stanford 2005

THANK YOU

QUESTIONS?

RESOURCES

railscasts.com

tryruby.org

ruby.railstutorial.org

railsforzombies.org

peepcode.com