Barry Jones introduces himself as the instructor for the Ruby on Rails and PostgreSQL course. He has experience developing applications using various languages and databases. He wishes a course like this had been available when he took over a large Perl to Rails conversion project without knowing Rails or PostgreSQL, which led to issues he later had to fix. The goal of the course is to help students gain proficiency with Rails and PostgreSQL faster to avoid similar mistakes.

1. Welcome to
Ruby on Rails and PostgreSQL

2. 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)

3. COURSE INTRODUCTION
Why are we here exactly?

4. 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

5. Why am I teaching this class?
• Learned Rails and PostgreSQL 2.5 years ago

6. 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

7. 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

8. How?
• Rails is great but…
• The community is largely
driven by DHH who
pushes doing everything
in 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

9. 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

10. 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

11. INTRO TO RUBY

12. 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

13. 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?

14. 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 processing
record = Record.find(id)
record.delay.some_intense_logic
• DelayedJob
• Resque
• Sidekiq
• Stalker
• Que
• QueueClassic
– Cross integrations
Email.deliver
• MailHopper – Automatically deliver all email in the background
• Gems that specifically enhance other gems

15. 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

16. 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

17. 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

18. 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'

19. 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

20. 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!”

21. 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

22. Object Variables
Instance Variable
• @my_variable = ‘bob’
Class Variable
• @@my_variable = ‘bob’

23. Accessors (get/set)
• class AccessorDemo
attr_accessor :hello
attr_reader :hello
attr_writer :hello
def initialize(hello = “World”)
# Constructor btw
@hello = hello
end
end

24. Error Handling
• raise (throw)
• regin (try)
• rescue (catch)
• Exception vs
StandardError
begin
raise “Whoops”
rescue StandardError => e
puts e.message
else
puts “All is well”
end

25. 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

26. The *splat operator
Method Definitions
def say(what, *people)
people.each do|person|
puts "#{person}: #{what}”
end
end
say "Hello!", "Alice", "Bob", "Carl"
# Alice: Hello!
# Bob: Hello!
# Carl: Hello!
Method Calls
people = ["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= 4
first, *center, last = [1,2,3,4] # first= 1, center= [2,3], last=4

27. 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)

28. Blocks and Yields
def my_method(&block)
puts “Before block”
&block.call
puts “After block”
&block.call #again
end
my_method do
puts “I like to do things!”
end
def my_method
puts “Before block”
yield
puts “After block”
yield # Call it all you want
end
my_method do
puts “I like to do things!”
end

29. 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
self
end

30. 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?

31. 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"]

32. Switch (Case/When)
• case a
when 1..5
# stuff
when String
# stuff
when /regexmatches/
# stuff
when 42
# stuff
else
# stuff
end

33. Mixins
module Persistence
def load sFileName
puts "load code to read #{sFileName} contents into my_data"
end
def save sFileName
puts "Uber code to persist #{@my_data} to #{sFileName}"
end
end
class BrandNewClass
include Persistence
attr_accessor :my_data
def data=(someData)
@my_data = someData
end
end
b = BrandNewClass.new
b.data = "My pwd"
b.save "MyFile.secret"
b.load "MyFile.secret"

34. Pry
def some_method
binding.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

35. RSpec
• before do
subject.stub(:big_calculation) { true }
end
it “should return a value that does things”
subject.big_calculation.should be_true
end

36. 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

37. The Ruby Warrior!
https://www.bloc.io/ruby-warrior/#/