Transcript Ruby on Rails

Ruby on Rails
Barry Burd
Drew University
[email protected]
Copy of these slides: http://www.burd.org/RoR.ppt
1
Agenda
• Ruby language
• Creating a Web application with Ruby on
Rails
• Fine tuning the Web application
• Doing other neat things
2
What is …?
• Ruby
– A simple, elegant, loosely typed, reflective,
interpreted programming language.
• Rails
– An add-on to Ruby for web/database
handling.
– Model-View-Controller
– Convention over configuration
– DRY philosophy
3
Ruby on Rails
• Advantage
– Lightning-fast prototyping
• Disadvantages(?)
– Development is not as fast with legacy db
– Development is not as fast if you customize
– Ruby programmers use Ruby idioms
– Difficult to deploy
– Security model isn’t as mature as Java EE
4
Hello world program
C:\ruby>irb --prompt simple
>> puts "Hello"
Hello
=> nil
>> exit
C:\ruby>
5
Defining and calling a method
C:\ruby>irb --prompt simple
>> def show(what)
>>
"You typed " + what + "."
>> end
=> nil
>> show("Hello")
=> "You typed Hello.“
>> puts show("Hello")
You typed Hello.
=> nil
6
Expression interpolation
>> def show(what)
>>
"You typed #{what}."
>> end
=> nil
>> puts show("Hello")
You typed Hello.
=> nil
>> def show(what)
>>
'You typed #{what}.'
>> end
=> nil
>> puts show("Hello")
You typed #{what}.
=> nil
7
Ruby is dynamically typed
(“duck typing”)
>> i = 7
=> 7
>> puts i, "\n"
7
=> nil
>> i = "Hello"
=> "Hello"
>> puts i
Hello
=> nil
8
Regular Expressions
>> line = "Perl"
=> "Perl"
>> if line =~ /Perl|Python/
>>
puts "Scripting language mentioned: #{line}"
>> end
Scripting language mentioned: Perl
=> nil
>>
=>
>>
>>
>>
=>
line = "Java"
"Java"
if line =~ /Perl|Python/
puts "Scripting language mentioned: #{line}"
end
nil
9
Blocks
>> def call_block
>>
puts "1"
>>
yield
>>
yield
>>
puts "3"
>> end
=> nil
>> call_block {puts "2"}
1
2
2
3
=> nil
10
Blocks with parameters
>> def call_block
>>
puts "1"
>>
yield(42)
>>
yield(79)
>>
puts "3"
>> end
=> nil
>> call_block {|x| puts x}
1
42
79
3
=> nil
11
>> 5.times {puts "*"}
*
*
*
*
*
=> 5
>> 3.upto(6) {|i| puts i}
3
4
5
6
=> 3
>> ('a'..'e').each {|char| puts char}
a
b
c
d
e
=> "a".."e"
12
Another Ruby program
C:\>type fact.rb
def fact(n)
return 1 if n == 0
f = 1
n.downto(1) do |i|
f *= i
end
return f
end
print fact(ARGV[0].to_i), "\n"
C:\>ruby fact.rb 10
3628800
C:\>ruby fact.rb 5
120
13
Ruby’s integers (and other things)
are of arbitrary size
C:\>ruby fact.rb 155
4789142901463393876335775239063022722
176295591337767174070096339929153381
622433264146569329274347655956110484
372311586936020749175429076661003216
274382475477806479918110524333880196
139452687559896255940215628508414806
740389616633144934400000000000000000
000000000000000000000
14
Ruby is object-oriented
class Point
def initialize(x, y)
@x = x; @y = y
self
end
def to_s
sprintf("%d@%d", @x, @y)
end
end
list1 = [10, 20, Point.new(2, 3), Point.new(4, 5)]
list2 = [20, Point.new(4, 5), list1]
print("list1: ", list1.inspect, "\n")
print("list2: ", list2.inspect, "\n")
C:\>ruby list3.rb
list1: [10, 20, #<Point:0x2867a48 @y=3, @x=2>,
<Point:0x2867a30 @y=5, @x=4>]
list2: [20, #<Point:0x28679e8 @y=5, @x=4>, [10, 20,
#<Point:0x2867a48 @y=3, @x=2>, #<Point:0x2867a30 @y=5,
@x=4>]]
15
Ruby has unit testing
class Adder
def initialize(number)
@number = number
end
def add(number)
return @number + number
end
end
require 'test/unit'
require 'adder'
class TC_Adder < Test::Unit::TestCase
def setup
@adder = Adder.new(5)
end
def test_add
assert_equal(7, @adder.add(2),
"Should have added correctly")
end
def teardown
@adder = nil
end
16
end
Class with a constructor
(from “Programming Ruby”)
class Song
def initialize(name, artist, duration)
@name = name
@artist = artist
@duration = duration
end
end
song = Song.new("Bicylops","Fleck",260)
17
Getters
# This code can come immediately after the previous
# slide’s code.
class Song
def name
@name
end
def artist
@artist
end
def duration
@duration
end
end
puts song.name
18
Quick way to create getters
class Song
attr_reader :name, :artist, :duration
end
puts song.name
19
>> class MyClass
>> end
=> nil
>> MyClass.methods
=> ["send", "name", "class_eval", "object_id", "new", "singleton_methods",
"__se
nd__", "private_method_defined?", "equal?", "taint", "frozen?",
"instance_variab
le_get", "constants", "kind_of?", "to_a", "instance_eval", "require",
"ancestors
", "const_missing", "type", "instance_methods", "protected_methods", "extend",
"
protected_method_defined?", "eql?", "public_class_method", "const_get",
"instanc
e_variable_set", "hash", "is_a?", "autoload", "to_s", "class_variables",
"class"
, "tainted?", "private_methods", "public_instance_methods", "instance_method",
"
require_gem_with_options", "untaint", "included_modules",
"private_class_method"
, "const_set", "id", "<", "inspect", "<=>", "==", "method_defined?", ">",
"===",
"clone", "public_methods", "protected_instance_methods", ">=", "respond_to?",
"
display", "freeze", "<=", "module_eval", "autoload?", "allocate", "__id__",
"=~"
, "methods", "require_gem", "method", "public_method_defined?", "superclass",
"n
il?", "dup", "private_instance_methods", "instance_variables", "include?",
"call
20
_block", "const_defined?", "instance_of?"]
Ruby is Reflective (1)
class Myclass
def mymethod
puts "Hello"
end
end
x = 'mymethod'
Myclass.new.send(x)
Hello
21
Ruby is Reflective (2)
class MyStuff
def announce
puts "I'm being announced.\n"
end
def method_missing(method_name)
puts "I don't know how to do #{method_name}.\n"
end
end
m = MyStuff.new
m.announce
m.xyz
I'm being announced.
I don't know how to do xyz.
22
Creating a web-based database application
in about a dozen steps…
23
Rails naming conventions
• company application
• company_development database
• employees table
• generate model Employee
• generate controller Employee
• employee_controller.rb
• EmployeeController class
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Using the Model to Validate Input
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Many-to-many relationships
require "rubygems"
require_gem "activerecord"
ActiveRecord::Base.establish_connection(
:adapter=> "mysql",
:host => "localhost",
:database => "company2_development")
class Task<ActiveRecord::Base
has_and_belongs_to_many :employees
end
56
Many-to-many relationships
class Employee < ActiveRecord::Base
has_and_belongs_to_many :tasks
def acquire_task(task)
tasks.push_with_attributes(task)
end
def show_task(i)
puts tasks.find(i).description
end
def show_tasks
for task in tasks
puts task.description
end
end
end
57
Many-to-many relationships
emp1 = Employee.new
emp1.name = 'Barry Burd'
emp1.salary = 100000000.0
emp1.fulltime = false
emp1.level = 10
emp1.hiredate = '2006-08-22‘
emp1.save
task = Task.new
task.description = "Clean the office"
task.save
task2 = Task.new
task2.description = "Scoop the cat litter"
task2.save
58
Many-to-many relationships
emp = Employee.find(1)
emp.acquire_task(Task.find(1))
emp.acquire_task(Task.find(2))
emp2.show_tasks
Clean the office
Scoop the cat litter
59
Ajax
60
In the controller...
def show_body
@comment = Comment.find(params[:id])
render :text => @comment.body
end
61
In the view...
<head>
<%= javascript_include_tag "prototype" %>
</head>
...
<% for comment in @comments %>
<tr>
<td><%= comment.title %></td>
<td>
<div id="comment_<%= comment.id.to_s %>">
<%= link_to_remote( "Show Body",
:update => "comment_#{comment.id.to_s}",
:url => { :action => :show_body,
:id => comment }) %>
</div>
</td>
62
Sending Email
63
The Message Model
class CreateMessages < ActiveRecord::Migration
def self.up
create_table :messages do |t|
t.column :subject, :string
t.column :custname, :string
t.column :amount, :float
t.column :recipients, :string
t.column :sender, :string
end
end
def self.down
drop_table :messages
end
end
64
Configuring the mailer
ActionMailer::Base.server_settings = {
:address => "mail.cheapprovider.net",
:domain => "burdbrain.com",
}
65
The Mailer class
class MyMailer < ActionMailer::Base
def setup(message, sent_at = Time.now)
@subject
= message.subject
@body['custname'] = message.custname
@body['amount']
= message.amount
@recipients = message.recipients
@from
= message.sender
@sent_on
= sent_at
@headers
= {}
end
end
66
Email template
<head>
<style type="text/css">
p.indent { margin-left: 60px }
</style>
</head>
<h1>Third Notice!</h1>
Dear <%= @custname %>,<p>
Your bill is overdue. Please pay
<%= number_to_currency(@amount) %> immediately.<p>
<p class="indent">Signed,<br>Your
<i><b>friends</b></i>
at Burd Brain Consulting</p>
67
How to mail a message
def create
@message = Message.new(params[:message])
my_message = MyMailer::create_setup(@message)
my_message.set_content_type 'text/html'
MyMailer::deliver my_message
if @message.save
flash[:notice] = 'Message was successfully
created.'
redirect_to :action => 'list'
else
render :action => 'new'
end
end
68
Creating a Web Service
69
Describing the Web Service
class TimeServiceApi <
ActionWebService::API::Base
api_method :get_time, :expects => [:bool],
:returns => [:time]
end
70
The Time Service
require 'time'
class TimeServiceController <
ApplicationController
wsdl_service_name 'TimeService'
web_service_scaffold :use_service
def get_time(gmt)
(gmt)?(Time.now.getgm):(Time.now)
end
end
71
Add-Ons
• LoginGenerator
http://wiki.rubyonrails.com/rails/pages/LoginGenerator
• Payment
http://payment.rubyforge.org/
• ActiveSearch
http://julik.nl/code/active-search/index.html
• Active Merchant
http://home.leetsoft.com/am/
• …and lots more!
72
References
• Home:
http://www.rubyonrails.com
• THE books:
Programming Ruby:
http://www.rubycentral.com/book/index.html
Agile Web Development with Rails
http://www.pragmaticprogrammer.com/title/rails/
• My book:
Ruby on Rails For Dummies
http://www.amazon.com/blah-blah-blah...
• Resources:
http://www.rubyquiz.com/
http://www.ruby-doc.org/
http://www.rubycentral.com/
http://railsmanual.org/
http://www.freeonrails.com/
http://tryruby.hobix.com/
• Rails Web hosting:
http://railsplayground.com/
http://www.railshosting.org/#free
http://www.rubyonrailswebhost.com/
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END
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