Avik_RailsTutorial

Ruby On Rails

A brief tutorial

Avik Sengupta

© 2005 Avik Sengupta. All Rights Reserved. 1

Agenda

Introduce Rails via these slides
Show me the code!
Code up a Rails application from scratch

(This tutorial assumes a very limited knowledge of
Ruby ... did you attend Premshree or Yogi's talks?)


Rails

“Rails is a full-stack, open-source web
framework in Ruby for writing real-world
applications with joy and less code than most
frameworks spend doing XML sit-ups”
Rails Creator - David H. Hansson


What is Rails

Full Stack
Model (Object Relation Mapping) – Active Record
View – Action View +ERb
Controller – Action Controller
Mail integration – ActionMailer
Web Services – Action Web services
..therefore, all layers work seamlessly (DRY)


The Rails request cycle


Active Record

Automated mappings :

Given this table..
CREATE TABLE entries (
id int(11) NOT NULL auto_increment,
name varchar(255),
comments varchar(255),
PRIMARY KEY (id)
);


Active Record
You can do
class Entry < ActiveRecord::Base
# nothing here!
end

entry = Entry.new
entry.name = "John"
entry.comments = "What a great Web site!"
entry.save

entry = Entry.find(1)
puts entry.name # output: "John"


Active Record

Associations only need to be declared
class Firm < ActiveRecord::Base
has_many :clients
has_one :account
belongs_to :conglomerate
end

firm.clients.each do |client| {...}
firm.has_clients?


Action Controller

Action Controller
Handles the entire request cycle
Actions grouped into Controller
Each action is method in the controller class
Instance variables are passed to the view

class GuestbookController <
ActionController::Base
def index
@entries = Entries.find_all
end
end

Views

Templates in Embedded Ruby (like JSP or ASP)
Expression language is Pure Ruby
Helper classes provide common functionality for
strings, dates, forms etc.
<html>
<body>
<h1>Cookbook</h1>
<% for e in @entries %>
<p><%= e.name %>: <%= e.description %></p>
<% end %>
</body>
</html>


Action Mailer

Integrate e-mails from Rails applications
# send email with attachment
def report_notification(recipient)
recipients recipient.email_address_with_name
subject "Your Report"
from "owner@app.com"

attachment :content_type => "image/gif", :body =>
File.read("logo.gif")

attachment "image/gif" do |a|
a.body = generate_chart()
end
end


Action Web Services

Server side WS and XML-RPC protocols
Export API's as Web Services


Demo
Build a web based cookbook, live, from scratch.

For reference, some of the steps we will go through are
illustrated in the following slides. However, for the tutorial,
we will write the code directly ourselves!


Downloads and Installation
Install Ruby
On Windows you can use the One-Click installer. For other
platforms, use your platform packages
Install RubyGems (a ruby package management
system)
Download from http://rubyforge.org/projects/rubygems/
Unpack the downloaded archive and in that directory run the
command:
ruby install.rb
Install Rails
From the command line execute: From the command line
execute:
gem install rails


First Steps

Generate Application Structure
$ rails cookbook
Create Database
Generate Models and Controllers
Use scaffold to create basic app


More code...

Flesh out the application
Create Views
Use partials and helpers
Use layouts
Implement Validations
Model complex relationships


Advanced Stuff

Callbacks
Transactions
Caching
Rails makes AJAX easy
Go to Vamsee Kankala's tutorial
Rails makes testing easy
Again, go to Vamsee's tutorial


Questions?

Curiosity killed the cat... or did it?


Credits

This presentation inspired by
Rolling with Rails (OnLamp) by Curt Hibbs
http://www.onlamp.com/pub/a/onlamp/2005/01/20/rails.html
Presentation at Chicago ACM by Ryan Platte and John
W. Long
http://www.ruby-doc.org/docs/Get to the Point Development with Ru


More Info

Main Ruby Site
http://www.ruby-lang.org
One Click Ruby Installer for Windows
http://rubyinstaller.rubyforge rubyforge.org
Main Rails Site
http://www.rubyonrails.org
This presentation
http://www.sengupta.net/talks/


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