Welcome toRuby on Rails and PostgreSQL

Make sure things are installed

• Windows

– Vagrant

– Virtual Box

– Vagrantfile

• OSX

– Homebrew

• Everybody

– RVM

If you haven’t already installed these, go ahead and start them now… (links in Hipchat room)

COURSE INTRODUCTION

Why are we here exactly?

Who am I?

• I’m Barry Jones

• Application Developer since ’98

– Java, PHP, Groovy, Ruby, Perl, Python

– MySQL, PostgreSQL, SQL Server, Oracle, MongoDB

• Efficiency and infrastructure nut

• Believer in “right tool for the job”

– There is no silver bullet, programming is about tradeoffs

Why am I teaching this class?

• Learned Rails and PostgreSQL 2.5 years ago

How I learned?

• Took over a large perl to rails conversion post-launch

• It did not go well

• Took over the entire project without knowing Rails or PostgreSQL

• It was an interesting year

So why am I teaching this class?

Reason 1

• I wish it had been available for me

• Could have gotten up to speed much faster

Reason 2

• I wish it had been available for the contractors

• Could have avoided a slew of mistakes that I had to fix

How?

• Rails is great but…

• The community is largely driven by DHH who pushes doing everythingin Rails

• Rails is not the solution for everything

• Ruby isn’t perfect. It’s awesome…but not perfect

• PostgreSQL is great but…

• There is no “but”, PostgreSQL is just great

• But…if you don’t know why it’s great or how to use it you will tend to favor doing everything in Rails…

• Or adding in 3rd party systems you don’t need

Understanding these two things will…

• Give you amazing tools

• Help you work faster

• Help you solve more problems

• Keep you from creating Kool-Aid induced issues

Now…who are you people?

Introduce yourselves

• Name

• Where are you from?

• Quick professional overview

• What do you want to get out of this class?

• Favorite Movie

INTRO TO RUBY

What do we look for in a language?

• Balance– Can it do what I need it to do?

• Web: Ruby/Python/PHP/Perl/Java/C#/C/C++

– Efficient to develop with it?• Ruby/Python/PHP

– Libraries/tools/ecosystem to avoid reinventing the wheel?• Ruby/Python/PHP/Java/Perl

– Is it fast?• Ruby/Python/Java/C#/C/C++

– Is it stable?• Ruby/Python/PHP/Perl/Java/C#/C/C++

– Do other developers use it?• At my company? In the area? Globally?

– Cost effective?• Ruby/Python/PHP/Perl/C/C++

– Can it handle my architectural approach well?• Ruby/Python/Java/C# handle just about everything• CGI languages (PHP/Perl/C/C++) are very bad fits for frameworks, long polling, evented programming

– Will it scale?• Yes. This is a subjective question because web servers scale horizontally naturally

– Will my boss let me use it?• .NET shop? C#• Java shop? Java (Groovy, Clojure, Scala), jRuby, jython• *nix shop? Ruby, Python, Perl, PHP, C, C++

• Probable Winners: Ruby and Python

What stands out about Ruby?

• Malleability– Everything is an object

– Objects can be monkey patched

• Great for writing Domain Specific Languages– Puppet

– Chef

– Capistrano

– Rails

“this is a string object”.length

class String

def palindrome?

self == self.reverse

end

end

“radar”.palindrome?

How is monkey patching good?

• Rails adds web specific capabilities to Ruby– “ “.blank? == true

• Makes using 3rd party libraries much easier– Aspect Oriented Development

• Not dependent on built in hooks

– Queued processingrecord = Record.find(id)

record.delay.some_intense_logic

• DelayedJob• Resque• Sidekiq• Stalker• Que• QueueClassic

– Cross integrationsEmail.deliver

• MailHopper – Automatically deliver all email in the background• Gems that specifically enhance other gems

How is monkey patching…bad?

• If any behavior is modified by a monkey patch there is a chance something will break

• On a positive note, if you’re writing tests and following TDD or BDD the tests should catch any problems

• On another positive note, the ruby community is very big on testing

Why was Ruby created?

• Created by Yukirio Matsumoto

• "I wanted a scripting language that was more powerful than Perl, and more object-oriented than Python.”

• "I hope to see Ruby help every programmer in the world to be productive, and to enjoy programming, and to be happy. That is the primary purpose of Ruby language.”– Google Tech Talk in 2008

Ruby Version Manager

• cd into directory autoselects correct version of ruby and gemset

• Makes running multiple projects with multiple versions of ruby and gem dependencies on one machine dead simple

.rvmrc file

rvm rubytype-version-patch@gemset

Examples:

rvm ruby-1.9.3-p327@myproject

rvm jruby-1.7.4@myjrubyproject

rvm ree-1.8.7@oldproject

.ruby-version file

ruby-2.1.2

.ruby-gemset file

myproject

Bundler and Gemfile

$ bundle install

Using rake (10.0.4)

Using i18n (0.6.1)

Using multi_json (1.7.2)

Using activesupport (3.2.13)

Using builder (3.0.4)

Using activemodel (3.2.13)

Using erubis (2.7.0)

Using journey (1.0.4)

Using rack (1.4.5)

Using rack-cache (1.2)

Using rack-test (0.6.2)

…

Your bundle is complete! Use `bundle show

[gemname]` to see where a bundled gem is

installed.

source 'https://rubygems.org'

source 'http://gems.github.com'

# Application infrastructure

gem 'rails', '3.2.13'

gem 'devise'

gem 'simple_form'

gem 'slim'

gem 'activerecord-jdbc-adapter’

gem 'activerecord-jdbcpostgresql-

adapter'

gem 'jdbc-postgres'

gem 'jruby-openssl'

gem 'jquery-rails'

gem 'torquebox', '2.3.0'

gem 'torquebox-server', '~> 2.3.0'

Foreman

Not Ruby specific but written in ruby

Used with Heroku

Drop in a Procfile

$ foreman start

CTRL + C to stop everything

Procfile

web: bundle exec thin start -p $PORT

worker: bundle exec rake resque:work QUEUE=*

clock: bundle exec rake resque:scheduler

Basic Syntax / Standards

• Indents are 2 spaces• Methods can include ! or ? Characters

– ! Indicates the object will be modified• Change a String rather than returning a changed String• Sort an array rather than returning a sorted copy

– ? Indicates a boolean return• Rather than including “is” or “has” as part of a method name, use a ?• .palindrome? VS is_palindrome

• Methods with arguments do not HAVE to include parentheses around them– User.new(“Bob”)– User.new “Bob”

• There are no ++ or -- options. Use += 1 or -= 1 for equivalent• foo ||= “bar” means

– If foo is not initialized or false, set to “bar”– foo || foo = “bar”

• to_s = String, to_i = Integer, to_f = Float, to_sym = Symbol• :bob.to_s == “bob”, “bob”.to_sym == :bob• Use :bob over and over, same object is used vs “bob” which creates a String• Embed code in strings with “My name is #{name} the extraordinary!”

Object Methods

Instance Method

• def leopard?false

end

Class Method

• def self.leopard?false

end

Implicit return- Last line is automatically returned

Explicit returns - return false

Object Variables

Instance Variable

• @my_variable = ‘bob’

Class Variable

• @@my_variable = ‘bob’

Accessors (get/set)

• class AccessorDemoattr_accessor :helloattr_reader :helloattr_writer :hello

def initialize(hello = “World”)# Constructor btw @hello = hello

endend

Error Handling

• raise (throw)

• regin (try)

• rescue (catch)

• Exception vsStandardError

beginraise “Whoops”

rescue StandardError => eputs e.message

elseputs “All is well”

end

Error Handling Shorthand

• def risky_method!raise “OMG!” if epic_fail?

end

risky_method! rescue “epic fail…smh”

• raise and rescue default to StandardError

• Methods automatically encompass a “begin” wrapper

The *splat operator

Method Definitionsdef say(what, *people)people.each do|person| puts "#{person}: #{what}”

endend

say "Hello!", "Alice", "Bob", "Carl"# Alice: Hello!# Bob: Hello!# Carl: Hello!

Method Callspeople = ["Rudy", "Sarah", "Thomas"]say "Howdy!", *people# Rudy: Howdy!# Sarah: Howdy!# Thomas: Howdy!

def add(a,b)a + b

end

pair = [3,7]add *pair# 7

Variable Assignment from Arrays

first, *list = [1,2,3,4] # first= 1, list= [2,3,4]*list, last = [1,2,3,4] # list= [1,2,3], last= 4first, *center, last = [1,2,3,4] # first= 1, center= [2,3], last=4

Hashes

• { :name => ‘Bob’, :rank => :general, :sn => 1 }• { name: ‘Bob’, rank: :general, sn: 1 }• person[:name]• HashWithIndifferentAccess: person[‘name’]

• def some_method(hash_opts)# do things…

end

some_method(name: ‘Bob’, sn: 1)

Blocks and Yields

def my_method(&block)puts “Before block”

&block.call

puts “After block”

&block.call #again

end

my_method doputs “I like to do things!”

end

def my_methodputs “Before block”

yieldputs “After block”

yield # Call it all you want

end

my_method doputs “I like to do things!”

end

find_each

Person.find_each(:conditions => "age > 21") do |person|person.party_all_night!

end

def find_each(options = {})find_in_batches(options) do |records|records.each { |record| yield record }

end

selfend

if / else / elsif / unless

• if true# do things

elsif 5 # do other things

else# do final things

end

• unless true# do some stuff

end

• Trailing syntax

puts “I see bob!” if bob?

puts “No bob!” if !bob?

puts “No bob!” unless bob?

Range operator

(-1..-5).to_a #=> []

(-5..-1).to_a #=> [-5, -4, -3, -2, -1]

('a'..'e').to_a #=> ["a", "b", "c", "d", "e"]

('a'...'e').to_a #=> ["a", "b", "c", "d"]

Switch (Case/When)

• case awhen 1..5

# stuffwhen String# stuff

when /regexmatches/# stuff

when 42# stuff

else# stuff

end

Mixins

module Persistencedef load sFileName

puts "load code to read #{sFileName} contents into my_data"end

def save sFileNameputs "Uber code to persist #{@my_data} to #{sFileName}"

endend

class BrandNewClassinclude Persistenceattr_accessor :my_data

def data=(someData)@my_data = someData

endend

b = BrandNewClass.newb.data = "My pwd"b.save "MyFile.secret"b.load "MyFile.secret"

Pry

def some_methodbinding.pry # Execution will stop here.puts 'Hello World' # Run 'step' or 'next' in the console to move here.

end

• step: Step execution into the next line or method. Takes an optional numeric argument to step multiple times. Aliased to s

• next: Step over to the next line within the same frame. Also takes an optional numeric argument to step multiple lines. Aliased to n

• finish: Execute until current stack frame returns. Aliased to f

• continue: Continue program execution and end the Pry session. Aliased to c

RSpec

• before dosubject.stub(:big_calculation) { true }

end

it “should return a value that does things” subject.big_calculation.should be_true

end

Try it out!

• Create a gemset

• Create a Gemfile

• Install a gem

• Create a ruby file with some experimental code

• Open a Ruby console

• Experiment with classes and structures presented here

The Ruby Warrior!

https://www.bloc.io/ruby-warrior/#/