Ruby on Rails

Hellow
Bart André Dirkjan

Hellow
Bart André Dirkjan

Laptops, apple

Development is more than coding

Ruby on Rails

Ruby on Rails

Language
Ruby on Rails

Language
Ruby on Rails
Framework

What are we doing today?
1 Ruby basics
2 Rails terminology / vision
3 Build something simple

What are we doing today?
1 Ruby basics
st ....
ut fir
B
2 Rails terminology / vision
3 Build something simple

Very simple example

Address Book
■ Generate a new Rails Application
■ Generate some stuff
■ Prepare the database
■ Start the application
■ View application and be excited!

Terminal

Terminal
$ rails address_book
create
create app/controllers
create app/helpers
create app/models
create app/views/layouts
create test/functional
create test/integration
...
create log/server.log
create log/production.log
create log/development.log
create log/test.log

Terminal
$ rails address_book
create
create app/controllers
create app/helpers
create app/models
create app/views/layouts
create test/functional
create test/integration
...
create log/server.log
create log/production.log
create log/development.log
create log/test.log
$ cd address_book

Terminal

Terminal
$ ./script/generate scaffold person name:string
exists app/controllers/
exists app/helpers/
create app/views/people
...

./script/destroy to undo
Terminal
$ ./script/generate scaffold person name:string
exists app/controllers/
exists app/helpers/
create app/views/people
...

Terminal

Terminal
$ rake db:migrate
== 00000000000000 CreatePeople: migrating =============
-- create_table(:people)
-> 0.0177s
== 00000000000000 CreatePeople: migrated (0.0180s) ====

rake db:rollback to undo
Terminal
$ rake db:migrate
== 00000000000000 CreatePeople: migrating =============
-- create_table(:people)
-> 0.0177s
== 00000000000000 CreatePeople: migrated (0.0180s) ====

⌘N

Terminal

Terminal
$ cd address_book

Terminal
$ cd address_book
$ ./script/server
=> Booting Mongrel
=> Rails 2.1.0 application starting on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
** Starting Mongrel listening at 0.0.0.0:3000
** Starting Rails with development environment...
** Rails loaded.
** Loading any Rails specific GemPlugins
** Signals ready. TERM => stop. USR2 => restart.
** Rails signals registered.
** Mongrel 1.1.4 available at 0.0.0.0:3000
** Use CTRL-C to stop.

http://localhost:3000/

http://localhost:3000/people

It all seems like magic...

You feel lost...

This is normal. It will pass.

Close all

Ruby

The basics
■ Objects
■ Variables
■ Methods
■ Inheritance & Modules
■ Blocks

Objects, variables & methods

Objects, variables & methods
class Person
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end

class name
Objects, variables & methods
class Person
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end

class name
Objects, variables & methods
instance
variable
class Person
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end

class name
Objects, variables & methods
instance
variable
class Person method
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end

class Person
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
Console: using a class

class Person
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
Console: using a class
>> andre = Person.new
>> andre.name = ‘Andre’

class Person
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
Console: using a class
>> andre = Person.new
>> andre.name = ‘Andre’
>> bart = Person.new
>> bart.name = ‘Bart’

class Person
attr_accessor :name
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
Console: using a class
>> andre = Person.new
>> andre.name = ‘Andre’
>> bart = Person.new
>> bart.name = ‘Bart’
>> bart.insults(andre, “dog”)
“Bart thinks Andre is a stupid dog!”

Inheritance
class Person
attr_accessor :name
end
class Student < Person
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end

Inheritance
Student inherits
class Person
attr_accessor :name from person
end
class Student < Person
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end

Modules

Person
Woman Man

Driving skill
Person
Woman Man

Driving skill
Person
Woman Man

Person
Driving skill
Woman Man

Person
Woman Man
Driving skill
Andre Bart

Modules
module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
class Person
attr_accessor :name
include Insulting
end

Creates an
Modules ‘Insulting’ module
module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
class Person
attr_accessor :name
include Insulting
end

Creates an
Modules ‘Insulting’ module
module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
Person
end
classes can
class Person
‘Insult’
attr_accessor :name
include Insulting
end

Creates an
Modules ‘Insulting’ module
module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
Person
end
classes can
class Person class Robot
‘Insult’
attr_accessor :name attr_accessor :name
include Insulting include Insulting
end end
Everyone can
insult now!

module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
class Person
attr_accessor :name
end
Console: extending on the fly

module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
class Person
attr_accessor :name
end
Console: extending on the fly
>> andre = Person.new
>> andre.name = “Andre”
>> andre.extend(Insulting)
nil

module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
class Person
attr_accessor :name
end
Console: extending on the fly
>> andre = Person.new
>> andre.name = “Andre”
>> andre.extend(Insulting)
nil
>> andre.insults(bart)
“Andre thinks Bart is a stupid cow!”

module Insulting
def insults(other, object=\"cow\")
\"#{name} thinks #{other.name} is a stupid #{object}!\"
end
end
class Person
attr_accessor :name
end
Console: extending on the flyWe could also extend
an entire class like this!
>> andre = Person.new
>> andre.name = “Andre”
>> andre.extend(Insulting)
nil
>> andre.insults(bart)
“Andre thinks Bart is a stupid cow!”

Man
Person
Driving skill
Insulting
Gardening

Man
Person
Driving skill
Insulting
Gardening How do we test if
this man can insult?

Duck-typing

If it walks like a duck and quacks like a
duck, it's a duck.
— Lisa Graves

andre.respond_to?(:insult)

Person
Woman Man

Person
Woman Man Driver

Person
Driving skill
Woman Man

Blocks

class Person
attr_accessor :name
end
Console: using blocks

class Person
attr_accessor :name
end
Console: using blocks
>> people
[<#Person:0x00 @name=”Andre”>,<#Person:0x00 @name=”Bart”>]

class Person
attr_accessor :name
end
Console: using blocks
>> people
[<#Person:0x00 @name=”Andre”>,<#Person:0x00 @name=”Bart”>]
>> people.map{ |item| “#{item.name} is kewl” }
[“Andre is kewl”, “Bart is kewl”]

class Person
attr_accessor :name
end
Console: using blocks also have: select, reject and inject to
We
work with collections!
>> people
[<#Person:0x00 @name=”Andre”>,<#Person:0x00 @name=”Bart”>]
>> people.map{ |item| “#{item.name} is kewl” }
[“Andre is kewl”, “Bart is kewl”]

You know Ruby!

You know Ruby! Sorta...

You know Ruby! Sorta...

PART II

Convention
over configuration

railsenvy.com

VIEW
MVC
MODEL
CONTROLLER

Models
Talk to the database, contain business logic
Controllers
Provide the glue, prepare data when needed
Views
Show the content to the user

You are not a beautiful and unique
snowflake. You are the same decaying
organic matter as everyone else, and we
are all a part of the same compost pile.
— Tyler Durden, Fight Club

SEE CHANGE
RESOURCE
ADD REMOVE

Show me
something
SEE CHANGE
RESOURCE
ADD REMOVE

Show me
something
SEE CHANGE
RESOURCE
Add someone
ADD REMOVE

Show me
something
SEE CHANGE
Change
something
RESOURCE
Add someone
ADD REMOVE

Show me
something
SEE CHANGE
Change
something
RESOURCE
Add someone
Delete stuff
ADD REMOVE

CREATE UPDATE
CRUD READ DELETE

CREATE UPDATE
CRUD READ DELETE

CREATE UPDATE
CRUD READ DELETE
HTTP !

POST
CREATE UPDATE
CRUD READ DELETE
HTTP !

POST
CREATE UPDATE
CRUD READ
GET
DELETE
HTTP !

POST PUT
CREATE UPDATE
CRUD READ
GET
DELETE
HTTP !

POST PUT
CREATE UPDATE
CRUD READ
GET
DELETE
DELETE
HTTP !

http://www.snowflake.org/people/1

UNIVERSAL
URI
IDE
NT
IFI
ER
RESOURCE

ADD POST /people

ADD POST /people
SEE GET /people

ADD POST /people
SEE GET /people
CHANGE PUT /people/1

ADD POST /people
SEE GET /people
CHANGE PUT /people/1
REMOVE DELETE /people/1

REPRESENTATIONAL STATE TRANSFER
REST

RAILS CONTROLLER ACTIONS

RAILS CONTROLLER ACTIONS
INDEX NEW EDIT
SHOW CREATE UPDATE
DESTROY

Building something...

Let’s get started

Choose a subject

2 hrs
IT WON’T BE ENOUGH...

First 15 minutes
■ You should have an idea
■ You should have a rough sketch
■ You should have thought of what models you need
■ You should think of their relation to each other
■ Pick an pair of models with a 1..* relationship
1
Student * Beer

Next 10 minutes
■ You should have a new rails app
$ rails [your_app_name]
■ You should have generated the models
$ ./script/generate scaffold [model_name] [attr]:[type
type = string, text, integer, float, boolean,
date, time, datetime
reserved attrs => type, version

mate .

App structure
- app
- models
- views
- controllers
- config
- db
- migrate

App structure
- app
- models the model files
- views
- controllers
- config
- db
- migrate

App structure
- app
- models the model files
- views templates for HTML
- controllers
- config
- db
- migrate

App structure
- app
- models the model files
- views templates for HTML
- controllers the controller files
- config
- db
- migrate

App structure
- app
- models the model files
- views templates for HTML
- controllers the controller files
- config basic configuration
- db
- migrate

App structure
- app
- models the model files
- views templates for HTML
- controllers the controller files
- config basic configuration
- db
- migrate database migrations

Migrations

db/migrate/00000000_create_people.rb
class CreatePeople < ActiveRecord::Migration
def self.up
create_table :people do |t|
t.string :name
t.timestamps
end
end
def self.down
drop_table :people
end
end

Create a ‘People’
db/migrate/00000000_create_people.rb
table on UP
class CreatePeople < ActiveRecord::Migration
def self.up
create_table :people do |t|
t.string :name
t.timestamps
end
end
def self.down
drop_table :people
end
end

Create a ‘People’
db/migrate/00000000_create_people.rb
With a ‘Name’ table on UP
String class CreatePeople < ActiveRecord::Migration
def self.up
create_table :people do |t|
t.string :name
t.timestamps
end
end
def self.down
drop_table :people
end
end

Create a ‘People’
db/migrate/00000000_create_people.rb
With a ‘Name’ table on UP
String class CreatePeople < ActiveRecord::Migration
def self.up
create_table :people do |t|
t.string :name
t.timestamps
end
end
def self.down
drop_table :people
And some time-stamps:
end
end
created_at & updated_at

Create a ‘People’
db/migrate/00000000_create_people.rb
With a ‘Name’ table on UP
String class CreatePeople < ActiveRecord::Migration
def self.up
create_table :people do |t|
t.string :name
t.timestamps
end
end
def self.down
drop_table :people
And some time-stamps:
end
end
created_at & updated_at
Drop the
table on
DOWN

Relationships

1
Student * Beer
app/models/student.rb
class Student < ActiveRecord::Base
has_many :beers
end
app/models/beer.rb
class Beer < ActiveRecord::Base
belongs_to :student
end

db/migrate/00000000_create_beers.rb
class CreateBeers < ActiveRecord::Migration
def self.up
create_table :beers do |t|
t.string :brand
t.references :student
t.timestamps
end
end
def self.down
drop_table :beers
end
end

db/migrate/00000000_create_beers.rb
Add a reference to Student
(:student_id)
class CreateBeers < ActiveRecord::Migration
def self.up
create_table :beers do |t|
t.string :brand
t.references :student
t.timestamps
end
end
def self.down
drop_table :beers
end
end

Next 10 minutes
■ You should update your model files when needed
belongs_to, has_many, has_one, has_many :through
■ You should add references to migrations
t.references :student

Next 5 minutes
■ You should have migrated the database
$ rake db:migrate
■ You should have a running server
$ ./script/server
■ You should see your app
$ open http://localhost:3000

Routes

config/routes.rb
ActionController::Routing::Routes.draw do |map|
map.resources :students
map.resources :beers
# You can have the root of your site routed with map.root
# map.root :controller => \"welcome\"
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
end

config/routes.rb
Routes for each resource
ActionController::Routing::Routes.draw do |map|
map.resources :students
map.resources :beers
# You can have the root of your site routed with map.root
# map.root :controller => \"welcome\"
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
end

config/routes.rb
Routes for each resource
ActionController::Routing::Routes.draw do |map|
map.resources :students
map.resources :beers
# You can have the root of your site routed with map.root
# map.root :controller => \"welcome\"
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
end
Remove # and
change :controller to ‘students’

ADD POST /people
SEE GET /people
CHANGE PUT /people/1
REMOVE DELETE /people/1
SEE GET /people/1
CHANGE GET /people/1/edit
ADD GET /people/new

Next 5 minutes
■ Change the routes
Uncomment & choose default controller
■ Remove ‘public/index.html’
$ rm public/index.html
■ Refresh your browser

ActiveRecord

One class per table
One instance per row

One class per utable
b tes
at tri
sare
lumn
Co
One instance per row

Student.find_by_name(“Andre”)
Student.find(:first, :conditions => [“name = ?”,”Andre”])

Student.find_all_by_name(“Andre”)
Student.find(:all, :conditions => [“name = ?”,”Andre”])

andre = Student.new( :name => “Andre” )
andre.save

Next 10 minutes
■ You should play with your app, create some instances
We created a student named “Andre”
■ You should start a console
$ ./script/console
■ You should build a few relationships using the console
>> andre = Student.find_by_name(“Andre”)
>> beer = andre.beers.create( :brand => “Grolsch” )
>> beer.student.name
”Andre”

Views

app/views/beer/new.html.erb
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %>
</p>
<p>
<%= f.submit \"Create\" %>
</p>
<% end %>
<%= link_to 'Back', beers_path %>

Title of the page
app/views/beer/new.html.erb
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %>
</p>
<p>
<%= f.submit \"Create\" %>
</p>
<% end %>
<%= link_to 'Back', beers_path %>

Title of the page
app/views/beer/new.html.erb
A form
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %>
</p>
<p>
<%= f.submit \"Create\" %>
</p>
<% end %>
<%= link_to 'Back', beers_path %>

Title of the page
app/views/beer/new.html.erb
A form
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %> Show errors messages if
</p>
<p> something goes wrong
<%= f.submit \"Create\" %>
</p>
<% end %>
<%= link_to 'Back', beers_path %>

Title of the page
app/views/beer/new.html.erb
A form
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %> Show errors messages if
</p>
<p> something goes wrong
<%= f.submit \"Create\" %>
Some fields </p>
<% end %>
and a button
<%= link_to 'Back', beers_path %>

Title of the page
app/views/beer/new.html.erb
A form
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %> Show errors messages if
</p>
<p> something goes wrong
<%= f.submit \"Create\" %>
Some fields </p>
<% end %>
and a button
<%= link_to 'Back', beers_path %>
Back link

app/views/beer/new.html.erb
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %>
</p>
<p>
<%= f.submit \"Create\" %>
</p>
<% end %>
<%= link_to 'Back', beers_path %>

app/views/beer/new.html.erb
<h1>New beer</h1>
<% form_for(@beer) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %>
</p>
<p>
<%= f.label :student %><br />
<%= f.collection_select :student_id, Student.find(:all), :id, :name %>
</p>
<p>
<%= f.submit \"Create\" %>
</p>
<% end %>
<%= link_to 'Back', beers_path %>

Next 15 minutes
■ Should be able to set a belongs_to relationship
collection_select
■ Relationship must be able to be set on new and
existing objects
Change both the edit and new view!
■ Test that it really works!
Try to edit the show view to represent the object relationship so
another human understands it!

Validations
This is a behaviour...

Validations
This is a behaviour...

BDD
BEHAVIOUR DRIVEN DEVELOPMENT

How should a student behave?

Student
■ should never have a blank name

Terminal

Terminal
$ ./script/generate rspec
create lib/tasks/rspec.rake
create script/autospec
create script/spec
create script/spec_server
create spec
create spec/rcov.opts
create spec/spec.opts
create spec/spec_helper.rb
create stories
create stories/all.rb
create stories/helper.rb

Terminal
$ ./script/generate rspec
create lib/tasks/rspec.rake
create script/autospec
create script/spec
create script/spec_server
create spec
create spec/rcov.opts
create spec/spec.opts
create spec/spec_helper.rb
create stories
create stories/all.rb
create stories/helper.rb
$ ./script/generate rspec_model student

Terminal
$ ./script/generate rspec
create lib/tasks/rspec.rake
create script/autospec
create script/spec
create script/spec_server
create spec
create spec/rcov.opts
create spec/spec.opts
create spec/spec_helper.rb
create stories
create stories/all.rb
create stories/helper.rb
$ ./script/generate rspec_model student
$ rake db:migrate RAILS_ENV=test

spec/models/student_spec.rb
require File.dirname(__FILE__) + '/../spec_helper'
describe Student do
it \"should never have a blank name\" do
no_name = Student.new( :name => “” )
no_name.should_not be_valid
end
end

spec/models/student_spec.rb
ActiveRecord objects
require File.dirname(__FILE__) + '/../spec_helper'
describe Student do
have a valid? method
it \"should never have a blank name\" do
no_name = Student.new( :name => “” )
no_name.should_not be_valid
end
end

require File.dirname(__FILE__) + '/../spec_helper'
describe Student do
it \"should never have a blank name\" do
no_name = Student.new( :name => “” )
no_name.should_not be_valid
end
end
Terminal: Running tests

require File.dirname(__FILE__) + '/../spec_helper'
describe Student do
it \"should never have a blank name\" do
no_name = Student.new( :name => “” )
no_name.should_not be_valid
end
end
Terminal: Running tests
$ ruby spec/models/student_spec.rb
F
Failed:
Student should never have a blank name (FAILED)
Finished in 0.1 seconds
1 examples, 1 failures, 0 pending

app/models/student.rb
class Student < ActiveRecord::Base
has_many :beers
validates_presence_of :name
end

app/models/student.rb
class Student < ActiveRecord::Base
has_many :beers
validates_presence_of :name
end

Next 5 minutes
■ Add Rspec to your project
./script/generate rspec
■ Generate specs for your models - don’t replace files!
./script/generate rspec_model [model-name]
■ Clean spec files. Make sure they look like this.
require File.dirname(__FILE__) + '/../spec_helper'
describe Student do
end
■ Build the test database
rake db:migrate RAILS_ENV=test

Next 15 minutes
■ Spec out all your validations
■ First, all your specs should fail
■ Add the validations to your models
validates_presence_of
validates_uniqueness_of
validates_format_of
validates_length_of
validates_numericality_of
■ Then, all your specs should pass

Connecting dots

.............
Connecting dots

Let’s make our view a little bit more fun

app/views/students/show.html.erb
<p>
<b>Name:</b>
<%=h @student.name %>
</p>
<%= link_to 'Edit', edit_person_path(@person) %> |
<%= link_to 'Back', people_path %>

app/views/students/show.html.erb
<p>
<b>Name:</b>
<%=h @student.name %>
</p>
<ul>
<% @student.beers.each do |beer| %>
<li> 1 x <%= h beer.brand %> </li>
<% end %>
</ul>
<%= link_to 'Edit', edit_person_path(@person) %> |
<%= link_to 'Back', people_path %>

Next 10 minutes
■ Pimp one of your views!

You all get a PDF version of this book
to continue working on your project,
thanks to pragprog.com
FREE!

</PRESENTATION>