Rapid Web Development With Ruby and Rails

A brief introduction to Ruby and Rails. Designed for programmers thinking about switching to Ruby on Rails.

Demo code at the end: https://github.com/jlong/cookbook

Transcript

1. Ruby & Rails Rapid web development with @johnwlong
2. What is Ruby? • A focus on simplicity & productivity • An elegant, natural syntax • Roots in Lisp, Perl, & Smalltalk A dynamic, object-oriented programming language with: Created by Yukihiro Matsumoto, a.k.a. Matz
3. Squeaky Clean • Ruby is purely object-oriented • Everything is an object • Even strings and numbers # Output "UPPER" puts "upper".upcase # Output the absolute value of -5: puts -5.abs # Output "Ruby Rocks!" 5 times 5.times do puts "Ruby Rocks!" end
4. Classes & Methods Classes begin with class and end with end: # The Greeter class class Greeter end Methods begin with def and end with end: # The salute method def salute end
5. Classes & Methods (p2) # The Greeter class class Greeter def initialize(greeting) @greeting = greeting end def salute(name) puts "#{@greeting} #{name}!" end end # Initialize our Greeter g = Greeter.new("Hello") # Output "Hello World!" g.salute("World")
6. If Statements # A simple if statement: if account.total > 100000 puts "large account" else puts "small account" end
7. If Statements (p2) # if with several branches if account.total > 100000 puts "large account" elsif account.total > 25000 puts "medium account" else puts "small account" end
8. Case Statements # A simple case/when statement case name when "John" puts "Howdy John!" when "Ryan" puts "Whatz up Ryan!" else puts "Hi #{name}!" end
9. Regular Expressions # Extract the parts of a phone number phone = "123-456-7890" if phone =~ /(\d{3})-(\d{3})-(\d{4})/ ext = $1 city = $2 num = $3 end Ruby supports Perl-style regular expressions:
10. Regular Expressions (p2) Regular expressions can also be used in case statements: # Case statement with regular expression case lang when /ruby/i puts "Matz created Ruby!" when /perl/i puts "Larry created Perl!" else puts "I don't know who created #{lang}." end
11. Blocks: Ruby’s Secret Sauce Blocks are like anonymous methods: # Print out a list of of people from # each person in the Array people.each do |person| puts "* #{person.name}" end # A block using the bracket syntax 5.times { puts "Ruby rocks!" } # Custom sorting [2,1,3].sort! { |a, b| b <=> a }
12. Yield to the Block! Use yield from within a method to hand control over to the block: # define the thrice method def thrice yield yield yield end # Output "Blocks are cool!" three times thrice { puts "Blocks are cool!" }
13. Blocks with Parameters You can also use parameters with yield: # redefine the thrice method def thrice yield(1) yield(2) yield(3) end # Output "Blocks are cool!" three times, # prefix it with the count thrice { | i | puts "#{i}: Blocks are cool!" }
14. Ruby is Highly Dynamic • Uses dynamic typing (vs. static) • Full support for introspection • Support for method and class redefinition • Create your own domain languages • Modules vs. multiple inheritance • method_missing, etc...
15. Dynamic Typing If it quacks like a duck... # The Duck class class Duck def quack puts "quack!" end end # The Mallard class (without inheritance) class Mallard def quack puts "qwuaacck!! quak!" end end
16. Dynamic Typing ...it must be a duck. def quack_em(ducks) ducks.each do |duck| if duck.respond_to? :quack duck.quack end end end birds = [Duck.new, Mallard.new, Object.new] quack_em(birds)
17. Introspection What are the methods of an object? Does an object have a method? irb> Object.methods => ["send", "name", "class_eval","object_id", "singleton_methods", ...] irb> Object.respond_to? :name => true
18. Domain Languages Ruby’s simple and powerful conceptual foundation allows for the creation of simple sub-languages called domain languages. An example from Rails: class Firm < ActiveRecord::Base has_many :clients has_one :account belongs_to :conglomorate end
19. Method Missing A simple proxy object: class Proxy def initialize(object) @object = object end def method_missing(symbol, *args) @object.send(symbol, *args) end end object = ["a", "b", "c"] proxy = Proxy.new(object) puts proxy.first # Outputs: "a"
20. Ruby on Rails • Active Record provides a database- driven model • Action Pack provides a tightly integrated view and controller: Action View & Action Controller Rails libraries form an MVC framework: Plus some: • Action Mailer • Active Support
21. How it Works Action Controller Active Record Action Mailer Action View Browser Response Request Deliveries
22. Active Record (Model) Automatically maps between tables, attributes, and columns. Given this table: CREATE TABLE recipes ( id int(11) NOT NULL auto_increment, title varchar(255), instructions varchar(255), PRIMARY KEY (id) );
23. Active Record (p2) You can do this: class Recipe < ActiveRecord::Base # nothing here! end recipe = Recipe.new recipe.title = "Frog Legs" recipe.instructions = "Boil in water!" recipe.save recipe = Recipe.find(1) puts recipe.title # output: "Frog Legs"
24. Action Controller • Handles entire request cycle • Actions are methods • Instance variables are passed to the view class RecipesController < ActionController::Base def index @recipe = Recipe.all end end
25. Action View Embed Ruby into HTML: <html> <body> <h1>Cookbook</h1> <% for recipe in @recipes %> <p><%= r.title %></p> <% end %> </body> </html>
26. What makes Rails great? • Convention over configuration • Domain specific languages • Magically wires up your objects • Easy way to build great web apps
27. Cookbook Application • Learn more about Ruby • Use Git for version control • Create a Recipes Model • Build a Recipes Controller • Dress up the Views • Twitter Bootstrap • Deploy to Heroku Let’s build a rails application from scratch!