RUBY on
OSDC.TW 2006

contagious

How Hot is RoR

450,000
over 400,000
downloads
337,500
225,000
112,500
0
2004 July 2004 Dec. 2005 Oct. 2006 April

• 400 seats, sold out in one week
• extra 150 seats, sold out in 24 hours

David
Heinemeier
Hansson

Data from BookScan:
Ruby Books sales is up 1,552%
over last year.

RoR is so HOT
Everybody wants to
clone it

What exactly is
Ruby On Rails

Ruby on Rails is an
open-source web
framework

optimized for
programmer
happiness

What Makes Programmer
Happy?
• Simplicity • Well organized
• Easy to learn • Easy to Maintain
• Easy to Write

SIMPLE
Easy to Learn and Write
No separation between
Business Logic and Display Logic

Corporate Approval
Well Structured
Steep Learn Curve
Complex Configuration
No fast turnaround

Finding the middle
ground with

Full Stack of MVC

Real World Usage

One Language - Ruby
• Model - View - Controller
• Database Schema generation
• Javascript generation
• XML generation
• Makefile

Convention
Over
Configuration

CREATE TABLE orders (
id INTEGER PRIMARY KEY AUTO_INCREMENT,
An
order_date TIMESTAMP NOT NULL,
price_total DOUBLE NOT NULL
);
example
CREATE TABLE products (
id INTEGER PRIMARY KEY AUTO_INCREMENT,
from a
name VARCHAR(80) NOT NULL,
price DOUBLE NOT NULL
);
Hibernate
CREATE TABLE order_items (
id INTEGER PRIMARY KEY AUTO_INCREMENT,
tutorial
order_id INTEGER NOT NULL,
product_id INTEGER NOT NULL,
amount INTEGER NOT NULL,
price DOUBLE NOT NULL
);

public class Order
Java
{
private Integer id;
private Date date;
private double priceTotal;
Object
private Set orderItems = new HashSet();
public Order() {
Model:
this.date = new Date();
}
public Integer getId() {
Order
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Date getDate() {
return date;
}
public void setDate(date) {
this.date = date;
}
public void addProduct(Product p, int amount) {
OrderItem orderItem = new OrderItem(this, p, amount);
this.priceTotal = this.priceTotal + p.getPrice() * amount;
this.orderItems.add(orderItem);
}
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
Java
<hibernate-mapping>
<class name="test.hibernate.Order" table="orders">
<id name="id" type="string" unsaved-value="null" >
<column name="id" sql-type="integer" not-null="true"/>
Database
<generator class="native"/>
</id>
<property name="date">
Mapping:
<column name="order_date"
sql-type="datetime" not-null="true"/>
</property>
Order
<property name="priceTotal">
<column name="price_total"
sql-type="double" not-null="true"/>
</property>
<set name="orderItems" table="order_items"
inverse="true" cascade="all">
<key column="order_id" />
<one-to-many class="test.hibernate.OrderItem" />
</set>
</class>
</hibernate-mapping>

Rails Data Model:
Order
class Order < ActiveRecord::Base
has_many :order_items
def add_product(product, amount)
order_item = OrderItem.new(product, amount)
self.price_total += product.price * amount
order_items << order_item
end
end

"opinionated software"
— sacrificing some
flexibility in favour of
simplicity

“much greater
productivity and a better
developer experience”

Dispatch based on URLs
http://myapp/orders/show/1
Application
controller
action
id
*customizable by Routing

Action grouped in Controller
class OrdersController < ApplicationController
def index
list
# Default to app/views/orders/index.rhtml
render :action => 'list'
end
def list
@order_pages, @orders =
paginate :orders, :per_page => 10
end
def show
@order = Order.find(params[:id])
end
end

Rendering and Redirection
def update
@order = Order.find(params[:id])
if @order.update_attributes(params[:order])
flash[:notice] =
'Order was successfully updated.'
redirect_to :action => 'show', :id => @order
else
render :action => 'edit'
end
end

Query Data
the_order = Order.find(2)
book = Product.find_by_name(”Programming Ruby”)
small_order = Order.find :first,
:condition => [”price_total <= ?”, 50.0]
web_books = Product.find :all,
:condition => [”name like ?”,”%Web%”]
print book.name
print the_order.price_total

Associations
class Order < ActiveRecord::Base
has_many :order_items
end
the_order = Order.find :first
the_oder.oder_items.each do |item|
print item.name
end
* Some other associations: has_one,
belongs_to, has_and_belongs_to_many...

Validations
class Product < ActiveRecord::Base
validates_presenc_of :name
validtaes_numericality :price
end
Hooks
class Order < ActiveRecord::Base
def before_destory
order_items.destory_all
end
end

Views - Erb
<!-- app/views/product/list.rhtml -->
<% for product in @products -%>
<p>
<ul>
<li> name: <%= product.name %> </li>
<li> price: <%= product.price %> </li>
</ul>
<%= link_to 'Show', :action => 'show',
:id => product %>
</p>
<% end -%>

Sounds Great !!
But it is written in ....
?? Ruby ??

Rails makes it fast to
develop, but the true
power behind Rails is
RUBY

Blocks
• Iteration
5.times { |i| puts i }
[1,2,3].each { |i| puts i }
• Resource Management
File.open(’t.txt’) do |f|
#do something
end
• Callback
TkButton.new do
text “EXIT”
command { exit}
end

New Language Construct
Rakefile
task :test => [:compile, :dataLoad] do
# run the tests
end
Markaby
html do
body do
h1 ‘Hello World’
end
end

Dynamic Nature
•Open Class
• Runtime Definition
• Code Evaluation
• Hooks

Meta - Programming
class Order < ActiveRecord::Base
has_many :order_items
end
class Product < ActiveRecord::Base
validates_presenc_of :name
validtaes_numericality :price
end

Syntax Matters
• Succinct
• Easy to Read
• Principle of Least Surprise

Ruby is designed to
make programmers
Happy

Where Rails Sucks
•Internationalization
• Speed
• Template System
• Stability
• Legacy System

Lack
Resources
In
Taiwan

Join Ruby.tw
http://willh.org/cfc/wiki/

Q&A