Everyday Rails

Everyday Rails
brought by Blaze Hadzik and

Blaze Hadzik
Ruby on Rails developer
blazej.hadzik@netguru.co

Poznan, Warsaw, Gdansk, Krakow
Australia, India, America, Brazil

‘Programming languages must feel
natural to programmers.’
Matz

Ruby is a dynamic, scripting, object-
oriented language...

:014 > 1.class
=> Fixnum
:015 > (2.2).class
=> Float
:016 > [].class
=> Array
:017 > "Politechnika Slaska".class
=> String
:018 > nil.class
=> NilClass
:019 > “abc” + “d”
=> “abcd”

variables
type local instance class global constant
example name @name @@name $name NAME
you don’t have to specify variable type

Variables
a = 12
a.class # => Integer
a = “polsl”
a.class # => String
a = [‘a’, ‘b’, ‘c’]
a.class # => Array

Arrays and Hashes
a = [ 'ant', 'bee', 'cat', 'dog', 'elk' ]
a[0] # => "ant"
a[3] # => "dog"
# this is the same:
a = %w{ ant bee cat dog elk }
a[0] # => "ant"
a[3] # => "dog"

Arrays and Hashes
my_hash = {
building: ‘school’,
fruit: ‘orange’
}
puts my_hash[:building] # => ‘school’

Symbols
LOW_PRIORITY = 0
HIGH_PRIORITY = 1
priority = HIGH_PRIORITY
vs
priority = :high
Symbols are simply constants that you don’t have to predeclare and that are guaranteed to be unique.

Control structures
if/else statements
case statements
while structure

Idioms
a, b = 1, 2
a += b
a # => 3
@a ||= 1 # @a = 1 if @a.nil?

Classes, objects
class School
def initialize(name)
@name = name
end
end
school = School.new(‘polsl’)
p school # =>#<School:0x007fa301836160 @name="polsl">

Class Attributes
class School
def initialize(name)
@name = name
end
def name=(name)
@name = name
end
def name
@name
end
end

Class Attributes
attr_reader
attr_writer
attr_accessor

Access Control
private
protected
public

‘It is impossible not to notice Ruby on Rails.’
Martin Fowler

Ruby is language
Rails is framework

controllers
models
views
routes.rb, database.yml
Gemfile

controller
model view
browser
DB
routes
web server

127.0.0.1 - GET /index.html HTTP/1.0" 200 2326

get ‘/’, to: ‘welcome#index’

class WelcomeController < ApplicationController
def index
@posts = Post.all
end
end

class Post < ActiveRecord::Base
end

<html>
…
<body>
…
<%= yield %>
…
</body>
</html

http://localhost:3000/http://localhost:3000/

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