This document provides an introduction to the Ruby programming language. It covers basic Ruby syntax like variables, conditionals, loops, arrays, hashes, and classes. It also discusses how to install and use Ruby on Rails, including generating scaffolds to quickly build out models, views, and controllers. Key topics covered include routes, controllers, models, views, databases, and the MVC framework pattern in Rails. Resources for learning more about Ruby and Rails are provided at the end.

2. I am Vysakh.
I am a web developer.

7. In Ruby
puts “Hello world”

9. Ruby is simply simple
Just like english

11. Variables

12. You have
- basket A with 10 apples
- basket B with 20 apples.
Find the sum and
difference

13. basketa = 10 apples
basketb = 20 apples
sum = basketa + basketb
=> 10 + 20 = 30
difference = basketb - basketa
=> 20 - 10 = 10

14. basket_a = 10
basket_b = 20
sum = basket_a + basket_b
difference = basket_b - basket_a
In Ruby

15. It is just like what you wrote in your
kindergarden answer sheet

16. Creator of Ruby - Matz

17. Running the code

18. Ruby is executed line by line
So output of a single line/logic can be seen
using irb

19. Opening up irb in the terminal
Instead of executing as a program file. Useful
for learning, debugging.

20. Conditionals

22. cold_weather = true
if cold_weather
puts “Wear something warm”
else
puts “Don’t wear something”
end
Ruby code

23. Most thing in Ruby is Object

24. 2.odd?()
=> false
“Vysakh”.length()
=> 6

25. Brackets are optional in Ruby
2.odd?
=> false
“Vysakh”.length
=> 6

26. Exercise 1
a) Get a string and check if it is palindrome.
b) Get a number and print the reverse of it.
Hint: use gets to get the input.

27. Array/List

29. In Ruby
shopping = [ “milk”, “cheese”, “olive oil”]

30. Loops

31. In Ruby
20.times do
puts “I must do my homework”
end

32. Also, there are
- loop
- while loop
- for loop
- step
- upto

33. HAPPY
Ruby is all about making programmer

34. Mam, please take
each item for me to
bill

35. cart = [“biscuit”, milk”, “shampoo”, “tampons” ]

36. Mam, please take
each item for me to
bill
cart = [“biscuit”, milk”, “shampoo”, “tampons” ]
cart.each do |item|
puts item
end

37. Exercise 2
- Create an array of marks you got in your
last assessment.
- Find if the sum of odd numbers is greater
than the sum of even numbers, if it is, you
have big odds at passing.
- Pass this information or bad luck will follow

38. HASH

39. In Ruby
slang = {
“lol” => “laugh out loud”,
“brb” => “Be right back”
}
slang[“lol”]
=> laught out loud

40. Use symbols instead of string
slang = {
:lol => “laugh out loud”,
:brb => “Be right back”
}
slang[:lol]
=> laught out loud

41. Symbols in Ruby
:hand.class
=> Symbol

42. Alternate way to write hash
slang = {
lol: “laugh out loud”,
brb: “Be right back”
}
slang[:lol]
=> laught out loud

43. Exercise 3
- Create a list of ipl team hashes
- with batsmen (3) name as key and their
sixes as values.
a) Find the sixes hit by a batsmen of a given
name

44. Functions

45. In Ruby
def y(x)
x**3
end
y(3) # => 27
y(2) # => 8

46. Exercise 4
a) Create a method rajini_style. Return his
dialogue (your favorite).
b) Create a factorial method that gets a
number and returns the factorial

47. Class

48. class Sports
def initialize(players, name)
@no_of_players = players
@name = name
end
end
cricket = Sports.new(11, “Cricket”)
foot_ball = Sports.new(11, “Football”)

49. Inheritance

51. a version manager (RVM or rbenv or other)
Install ruby using

52. rbenv
Installing Ruby using

54. Installing and setting Ruby

58. dhh
Creator of Ruby on Rails

60. Installing Rails

61. Creating a new rails project

62. Files generated with “rails new
myproject” command

63. Starting Rails server

64. Check the browser
localhost:3000

66. Understanding Rails

67. A dress shop
Pant
section?
1st floor
kid. 2nd
section

68. 1st floor
here is
your pant

69. A Rails server
/about
routes.rb
home
controller,
about
action

70. A Rails server
home controller,
about action
here is
your html
file

71. Lets do it in Rails

72. filename: config/routes.rb
Configure the routes to get /about

74. The corresponding html

75. and go to ‘/about’ url
Lets open the browser

77. available in the section?
When the pant is not
Coming back to the kid and pant story

78. 1st floor
I want this
specific
design
Godown
Oh kid
lemme go
to the
godown
and get

79. In Rails
Database
home controller,
about action
/posts/1

80. and have an abstraction(model)
Lets create a table

81. This will create model,
migration files

82. migration - A ruby file that will create, modify
tables
posts table
title column of type
string

83. from the ruby file(migration)
Lets create the tables

84. Rake, a simple ruby build program with
capabilities similar to make
This creates the posts table

85. table records through Rails model
Lets create, manipulate

86. Post is a Ruby class that Inherits ActiveRecord
app/models/post.rb

87. Object Relation Mapping(ORM) layer
Active Record is an

88. tables map to classes,

89. rows map to objects
rows map to objects
Rows map to objects
Columns map to object attributes

91. Few operations

92. Lets use this query in
Rails controller and give it to the user

94. Configure the routes file

95. Open up the browser

96. Show the title, description in html
app/views/show.html.erb

97. Now lets check the browser

98. Now lets do all this in
one command -> scaffold

101. This will generate all files
based on REST Architecture

102. Guides and resources

103. http://tryruby.org
http://www.codecademy.com/en/tracks/ruby
http://ruby.learncodethehardway.org/book/
Ruby

104. Ruby on Rails
railstutorial.org/book
railsforzombies.org
guides.rubyonrails.org/getting_started
railscasts.com

105. Local Ruby Community - chennair.b
Mailing list - google groups
Meetups - www.meetup.com/chennai-ruby