Developing Web Application using Ruby on Rails

Ben CurrenCTO and Founder

AgendaAgenda What is Ruby on Rails?

Overview of Rails

Create a Todo List Web Application using Rails

Introduction to Ruby

More Information

Questions

My BackgroundMy Background Started developing Java in 1996

Developed many web based applications using Java / J2EE, PHP and ASP.net.

Have worked extensively with C++ / C developing Windows desktop applications.

Developed desktop application using WinForms and .Net 1.1.

Have been working with Ruby on Rails for about months.

CTO and Founder of Esomnie. We develop web applications using Ruby on Rails, Java, and ASP.net.

Assumptions about the audienceAssumptions about the audience

I have made a couple assumptions about the audience: You have experience with an object-oriented programming language. You understand the basics of HTTP. You understand XHTML / HTML

What is Ruby on Rails?What is Ruby on Rails?

Rails is a web development framework

Ruby is a programming language

Rails is developed in Ruby.

Overview of Rails

What is Rails?What is Rails?

Full stack web application framework

Open source and Free

Active and growing community

What does Rails Provide?What does Rails Provide? MVC

ActiveRecord

Unit Testing Framework

Migrations

And ActiveResource, ActionWebService, ActiveSupport, ActionMailer, ActionPack

Rails OpinionsRails Opinions

Convention over configuration

Agile software development

Test driven development

Create a Todo List Web Application using Rails

The applicationThe application

A web application that allows a user to create a todo list

Users will be able to view a list of their todo lists.

Users will be able to create new todo lists.

They will be able to add items to the list. (not today, we will not have time)

Create the projectCreate the project

Create a new rails project named todo.

Creates the rails directory structure and initial configuration.

rails todo

Directory StructureDirectory Structuretodo

app

controllers

helpers

models

views

layouts

config

db

public

script

test

functional

unit

integration

vendor

…

Create the databases Create the databases

Create a file called db/create.sql

Run the script with mysql -uroot -p < db/create.sql

create database todo_development;

create database todo_test;

create database todo_production;

grant all on todo_development.* to 'tododev'@'localhost' identified by 'tododev';

grant all on todo_test.* to 'todotest'@'localhost' identified by 'todotest';

grant all on todo_production.* to 'todo'@'localhost' identified by 'todo';

Update the Database ConfigurationUpdate the Database Configuration Supply the username and password in config/database.yml

development: adapter: mysql database: todo_development username: tododev password: tododev host: localhost

test: adapter: mysql database: todo_test username: todotest password: todotest host: localhost

production: adapter: mysql database: todo_production username: todo password: todo host: localhost

Generate the List modelGenerate the List model

Create the List model.

It will hold the name of the todo list.

script/generate model list exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/list.rb create test/unit/list_test.rb create test/fixtures/lists.yml create db/migrate create db/migrate/001_create_lists.rb

Create the List MigrationCreate the List Migration A migration allows you to modify the database schema using Ruby.

Migrations provide versioning.

Update the file called db/migrate/001_create_lists.rb

class CreateLists < ActiveRecord::Migration def self.up create_table :lists do |t| t.column "name", :string t.column "created_at", :string t.column "updated_at", :string end end

def self.down drop_table :lists endend

Run the MigrationsRun the Migrations

rake migrate

(in /Users/bcurren/projects/todo)

== CreateLists: migrating ================================

-- create_table(:lists)

-> 0.4252s

== CreateLists: migrated (0.4269s) =======================

The List ModelThe List Model Without writing any mapping code, you can start using the List model.

Here are the contents of app/model/list.rb

class List < ActiveRecord::Baseend

Create and Store a List ObjectCreate and Store a List Objectscript/console

Loading development environment.

>> list = List.new

=> #<List:0x256680c @attributes={"name"=>nil, "updated_at"=>nil, "created_at"=>nil}, @new_record=true>

>> list.name = "Ben's Todo List"

=> "Ben's Todo List"

>> list.save

=> true

Require List.nameRequire List.name

Make the name of the list required.

Update the contents of app/model/list.rb

class List < ActiveRecord::Base

validates_presence_of :name

end

Test that List.name is requiredTest that List.name is required Add a test to make sure name is required. (test/unit/list_test.rb)

class ListTest < Test::Unit::TestCase

fixtures :lists

def test_name_required

List.new do |list|

list.name

assert !list.valid?

assert list.errors.on(:name)

end

end

end

Run the Unit TestsRun the Unit Testsrake test:unit

(in /Users/bcurren/projects/todo)

/usr/local/bin/ruby -Ilib:test "/usr/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb" "test/unit/list_test.rb"

Loaded suite /usr/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader

Started

Finished in 0.103404 seconds.

1 tests, 2 assertions, 0 failures, 0 errors

Rails MVC OverviewRails MVC Overview

Create the list of todo listsCreate the list of todo lists

Create a list controller with an action named list

The action list uses the model to get all the todo lists and places them in a variable called @lists

Create a view the loops over the @lists and renders the html view

Create the ListControllerCreate the ListController

script/generate controller List list

exists app/controllers/

exists app/helpers/

create app/views/list

exists test/functional/

create app/controllers/list_controller.rb

create test/functional/list_controller_test.rb

create app/helpers/list_helper.rb

create app/views/list/list.rhtml

The ListController The ListController

The generated file app/controllers/list_controller.rb

class ListController < ApplicationController

def list

end

end

The list actionThe list action Need to create an array of List objects in the database.

app/controllers/list_controller.rb

class ListController < ApplicationController

def list

@lists = List.find :all

end

end

The ListControllerTestThe ListControllerTest The generated list controller test in

test/functionals/list_controller_test.rb

class ListControllerTest < Test::Unit::TestCase

def setup

@controller = ListController.new

@request = ActionController::TestRequest.new

@response = ActionController::TestResponse.new

end

end

The test for the list actionThe test for the list action I added the test for the list action in The generated list

controller test in test/functionals/list_controller_test.rb.

def test_list

get :list

assert_response :success

assert_template 'list'

assert_not_nil assigns(:lists)

end

Run the functional testsRun the functional testsrake test:functionals

(in /Users/bcurren/projects/todo)

/usr/local/bin/ruby -Ilib:test"/usr/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb" "test/functional/list_controller_test.rb"

Loaded suite /usr/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader

Started

Finished in 0.095025 seconds.

1 tests, 3 assertions, 0 failures, 0 errors

The list viewThe list view

Update the template app/views/list/list.rhtml to display a list of the todo lists.

<h1>Todo Lists</h1>

<ul id="todo_list">

<%= render :partial => 'list',

:collection => @lists %>

</ul>

The list partialThe list partial

Create a file name app/views/list/_list.rhtml to display each list item.

<li><%= list.name %></li>

Check your workCheck your work Start up the web server. WEBrick comes with Rails and is great for

testing.

script/server &

[1] 6686

harley:~/projects/todo bcurren$ => Booting WEBrick...

=> Rails application started on http://0.0.0.0:3000

=> Ctrl-C to shutdown server; call with --help for options

[2006-10-08 09:50:46] INFO WEBrick 1.3.1

[2006-10-08 09:50:46] INFO ruby 1.8.4 (2005-12-24) [powerpc-darwin8.6.0]

[2006-10-08 09:50:46] INFO WEBrick::HTTPServer#start: pid=6686 port=3000

View the list in the browserView the list in the browser

Open your browser and type in the URL http://localhost:3000/list/list

Add a default layout to your pagesAdd a default layout to your pages Create a layout named app/views/layouts/default.rhtml

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

<head>

<%= javascript_include_tag :defaults %>

</head>

<body>

<%= @content_for_layout %>

</body>

</html>

Add the layout to the ApplicationControllerAdd the layout to the ApplicationController

Open the file app/controllers/application_controller.rb

All of the controllers in the app will now use the layout default. You can override this in each controller.

class ApplicationController < ActionController::Base

layout 'default'

end

Create a new todo list using AJAXCreate a new todo list using AJAX First, let’s create the form on the app/views/list.rtml page.

<div>

<%= form_remote_tag(

:url => {:controller => 'list', :action => 'add'},

:html => {:id => 'add_item_form',}) %>

<label for="list_name">Name:</label>

<%= text_field 'list', 'name', :size => 20 %>

<%= submit_tag 'Create' %>

<%= end_form_tag %>

</div>

Create the add actionCreate the add action

Add the following action to app/controllers/list_controller.rb

def add

@list = List.new(params[:list])

@list.save!

end

Create the add rjs fileCreate the add rjs file

Create a file named app/views/list/add.rjs

page.insert_html :bottom, "todo_list", :partial => 'list'

page.visual_effect :highlight, "todo_list"

page.form.reset 'add_item_form'

Test the AJAX addTest the AJAX add

The functional test requires a plugin and I don’t have time to include it here. See http://glu.ttono.us/articles/2006/05/29/guide-test-driven-rjs-with-arts for a good example.

http://localhost:3000/list/list

The application statsThe application statsrake stats

(in /Users/bcurren/projects/todo)

+----------------------+-------+-------+---------+---------+-----+-------+

| Name | Lines | LOC | Classes | Methods | M/C | LOC/M |

+----------------------+-------+-------+---------+---------+-----+-------+

| Helpers | 5 | 4 | 0 | 0 | 0 | 0 |

| Controllers | 16 | 12 | 2 | 2 | 1 | 4 |

| Components | 0 | 0 | 0 | 0 | 0 | 0 |

| Functional tests | 20 | 16 | 2 | 3 | 1 | 3 |

| Models | 3 | 3 | 1 | 0 | 0 | 0 |

| Unit tests | 13 | 11 | 1 | 1 | 1 | 9 |

| Libraries | 0 | 0 | 0 | 0 | 0 | 0 |

| Integration tests | 0 | 0 | 0 | 0 | 0 | 0 |

+----------------------+-------+-------+---------+---------+-----+-------+

| Total | 57 | 46 | 6 | 6 | 1 | 5 |

+----------------------+-------+-------+---------+---------+-----+-------+

Code LOC: 19 Test LOC: 27 Code to Test Ratio: 1:1.4

Introduction to Ruby

What is RubyWhat is Ruby

Object-oriented, dynamic scripting language

Developed by Yukihiro Matsumoto in 1995

Flexible and simple syntax

Based on Perl, Smalltalk, Eiffel, Ada and Lisp

Ruby is Object-OrientedRuby is Object-Oriented default_expiration_date is a public static method of CreditCard

day is a method of FixNum

day returns the number of seconds in x days

from_now is a method of FixNum

from_now returns the x seconds from now

class CreditCard

def self.default_expiration_date

1.day.from_now

end

end

Ruby is DynamicRuby is Dynamic Ruby has open classes.

You can open up a class and add or override methods.

The methods day and from_now are not part of the Ruby FixNum class. Rails adds them with the ActionPack module.

class FixNum

def days

self * 24.hours

end

alias :day :days

end

Ruby is Really DynamicRuby is Really Dynamic Add methods, instance, methods and more at runtime.

This can create an accessor and instance variable like this.

class CreditCard

attr_writer :number

end

Adding methods and variables at runtimeAdding methods and variables at runtime

attr_writer could be implemented like this.

class Object

def self.attr_writer(method)

eval %Q{

def #{method.to_s}=(value)

@#{method.to_s} = value

end

}

end

end

The Magic of method_missingThe Magic of method_missing

How would you write a method that prints out its name if the method name starts with print_?

For example: Example.print_my_name prints “print_my_name”

class Example

def self.method_missing(method_name, *args)

puts method_name if method_name =~ /^print_/

end

end

Ruby’s Closures (Blocks)Ruby’s Closures (Blocks) A closure allows a programmer to provide a block of code for a

method to run.

This example prints out each search engine. (taken from www.ruby-lang.org)

search_engines =

%w[Google Yahoo MSN].map do |engine|

“http://www.” + engine.downcase + “.com”

end

Implementation of Array.mapImplementation of Array.map

Here is an implementation of Array.map

class Array

def map(array)

new_array = Array.new

array.each {|element| new_array << yield element }

new_array

end

end

Ruby has Much More … Ruby has Much More …

Mixins - a collection of methods you can include into any class

Exception handling

Garbage collection

Single inheritance

Duck typing (no interfaces)

More Information

Deploying Rails ApplicationsDeploying Rails Applications

Rails apps are compatible with Unix and Windows environments

Rails apps can be deployed on multiple web server configurations Mongrel - Ruby web server, high performace and is currently the recommended

server WEBrick – a standalone Ruby web server, easy for development FastCGI – running behind Apache or LightTPD. Many problems with this.

Easy control of the deployment with Capistrano A scripting tool to control the deployment of the application on multiple sites

Easy control of schema migration rake migrate VERSION=3

More InformationMore Information Books

Agile Web Development With Rails

(get the second edition) Rails Recipes The Ruby Pick Axe Book

Active and growing community wiki.rubyonrails.com api.rubyonrails.com

FeedbackFeedback

Please provide feedback. Was this too detailed? Should I give more of an overview? Did I move to quickly / slow? Do you like a presentation with this much code? Did you like that I deveoped an example?

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My Contact InformationMy Contact Information

Ben Curren

ben@esomnie.com

Web site: www.esomnie.com

Blog: www.jotthought.com

Interested in a contract or full-time job? Email jobs@esomnie.com.

Questions?Questions?