Ruby on Rails TKK, Otto Hilska

Transcription

1 Ruby on Rails TKK, Otto Hilska 1

2 Today s agenda 1. The Ruby programming language 2. Ruby on Rails framework 3. An example project 2

3 About me Started Nodeta Oy in employees always recruiting focus on Ruby on Rails web development Ruby on Rails since 2005 Working on a global Rails project since

4 Ruby is... dynamic interpreted object-oriented productive, enjoyable not very fast 4

5 Ruby s history Yukihiro Matz Matsumoto started the project around 1995 Most developers were Japanese... and so were the mailing lists. 5

6 Ruby today Huge hype around Ruby on Rails open-sourced in July 2004 Enterprises have adopted Ruby Several Ruby implementations JRuby 6

7 Motivation Productive Fun Ruby on Rails 7

8 IDEs RubyMine Aptana RadRails Netbeans 8

9 Text editors 9

10 Some examples you can try these at 10

11 % irb >> a = 3 => 3 >> puts a => nil 11

12 >> 1337 ** 3 =>

13 >> 1337.class => Fixnum >> (1337 ** 3).class => Bignum 13

14 >> 3.times { puts "hello world" } hello world hello world hello world => 3 14

15 def fib(n) return 0 if n == 0 return 1 if n == 1 fib(n-1) + fib(n-2) end function declaration explicit return comparison reverse-if implicit return function call puts fib(15) 15

16 a = [ otto, veikko, mauno, juhani, veikko ] puts a.sort.uniq.join(, ) juhani, mauno, otto, veikko 16

17 Naming conventions Variables: age, total_length Constants: MAXIMUM_LENGTH Classes and modules: WebServer, ApplicationController Methods: age, age=, is_alive?, kill! 17

18 Other conventions 2 space indents File names: class ApplicationController lives in application_controller.rb 18

19 Common types Fixint and Bigint: 5, Float: 3.14 String: hello world Symbol: :utc Array: [1, 2, 3, text, 4.0], %w(array of strings) Hash: { :name => Otto, : => mutru@mutru.fi }, my_hash[:name] = Otto Range:

20 20

21 Type conversions a = => 5 b = a * 3 => aaa a + b TypeError: String can't be coerced into Fixnum a.to_s + b => 5aaa 21

22 Type conversions 4.to_f => to_s => 5 6.to_i => 6 6.to_f => 6.0 utc.to_sym => :utc :utc.to_s => utc 123 apples.to_i => 123 one beer.to_i => 0 22

23 Error handling begin require rubygems rescue LoadError => ex raise Please install Ruby gems end 23

24 Object-oriented programming (OOP) 24

25 Everything is an object Hello world.length 10.times { puts hello world } 10.class 10.class.class 25

26 class Apple < Fruit Writing a class attr_accessor :color def eat puts A #{color} apple was eaten. end end a = Apple.new a.color = green a.eat 26

27 Duck typing If it walks like a duck and quacks like a duck, I would call it a duck. 27

28 Duck typing in real life def eat_something(object) if object.respond_to?(:eat) object.eat else send(:eat) puts Don t know how to eat this. end end 28

29 Closures arr.sort { a, b a.name <=> b.name } arr.sort_by(&:name) 29

30 Closures arr = (1..10).to_a => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] arr.find_all { a a % 2 == 0 } => [2, 4, 6, 8, 10] 30

31 Yield def benchmark start_time = Time.now yield time_diff = Time.now - start_time puts Took #{time_diff} seconds end benchmark { fib(30) } 31

32 Metaprogramming 32

33 method_missing class MyFinder def method_missing(method_name) puts I m finding #{method_name} for you! end end m = MyFinder.new m.oranges 33

34 What if... A database query could be written as: User.find_by_name( Otto Hilska ) That s exactly how it works in Rails. 34

35 Too exciting! Let s have a short break. 35

36 Ruby on Rails 36

37 Background Open-sourced in 2004 Written by David Heinemeier Hansson Extracted from the Basecamp project management software 37

38 Motivation You can probably write your project in 15 minutes if you know what you re doing. you probably don t Case: tickets.assembly.org 38

39 Disclaimer 3 hours is not enough Focus on the big picture

40 Design principles Don t Repeat Yourself Convention over Configuration 40

41 HTTP Browsers send stateless requests Servers may store session information (state) 41

42 MVC Model stores and processes data contains the re-usable logic View renders data HTML, JavaScript, XML,... Controller processes HTTP requests has the request information and session information available uses models to do the business logic decides which views to render is supposed to be thin 42

43 Starting a Rails project: % rails myproject 43

44 Directory structure app controllers helpers models views layouts db migrate schema.rb tmp config database.yml environment* initializers routes.rb lib log public script test vendor 44

45 Today s example project Mutter my own Twitter clone because 140 chars is too much 45

46 Now some coding... 46

47 Summary DRY CoC Did you see any XML? 47

48 Deployment Many bad alternatives One good: 48

49 Further reading REST clients: rest-client and ActiveResource