Ruby on Rails for beginners

I am Vysakh.
I am a web developer.

In Ruby
puts “Hello world”

Ruby is simply simple
Just like english

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

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

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

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

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

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

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

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

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

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.

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

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

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

HAPPY
Ruby is all about making programmer

Mam, please take
each item for me to
bill

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

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

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

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

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

Symbols in Ruby
:hand.class
=> Symbol

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

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

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

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

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”)

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

Files generated with “rails new
myproject” command

Check the browser
localhost:3000

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

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

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

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

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

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

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

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

and have an abstraction(model)
Lets create a table

This will create model,
migration files

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

from the ruby file(migration)
Lets create the tables

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

table records through Rails model
Lets create, manipulate

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

Object Relation Mapping(ORM) layer
Active Record is an

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

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

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

Now lets do all this in
one command -> scaffold

This will generate all files
based on REST Architecture

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

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

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

Ruby on Rails for beginners

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