This document provides an overview of Ruby on Rails and PostgreSQL. It discusses that Ruby on Rails is a web application framework built with Ruby. It also discusses that PostgreSQL is a database that can be used with Rails through the pg gem. Finally, it provides tips on using RVM, migrations, Heroku, testing, and other Rails topics.

1. Ruby-on-Rails
&
PostgreSQL
John Ashmead

2. Ruby-on-Rails
•
Based on Ruby
•
A Framework, like Django
•
Widely popular
•
Ruby + ActiveRecord + Lots of Web Stuff + Lots of
other Stuff
•
Michael Hardt: http://ruby.railstutorial.org

3. Ruby Version
Manager
•
RVM lets you run multiple versions of ruby
•
Copies everything into some trees, then switches
pointers around
•
Manages gems & gemsets
•
Bundle install, bundle update

4. Gemfile
source 'https://rubygems.org'
!
ruby '2.0.0'
!
# Make sure we are using latest ‘rails’
gem 'rails', '4.0.0'
!
# Use Postgres as the database for Active Record
gem 'pg'
!
# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.0'
!
# switch to bootstrap, rspec, factory_girl, selenium,
capybara
!
…

5. ActiveRecord
•
Database adaptor
id
•
General purpose
name
•
Convention over
configuration
•
Reasonable defaults
•
Standalone product
maps
description
created_at
updated_at

6. Finally, PostgreSQL
•
‘pg’ gem
•
Provides ActiveRecord with
interface to Postgres
•
AR has an “execute”
function that lets you run
raw sql
•
‘postgres-pr’ gem gives
access to PostgreSQL
specific features, if needed

7. Foreign Keys
•
ActiveRecord has a lot of “associations”
•
Has_many, belongs_to, has_and_belongs_to_many
•
Doesn’t clean up the existing database
•
Doesn’t automatically generate the relevant keys
•
Doesn’t fix the metadata

8. create_table "maps", force: true do |t|
t.integer "user_id"
t.string
"map_type",
t.string
"name"
t.text
"description"
t.decimal "map_width"
t.decimal "map_height"
t.datetime "created_at"
t.datetime "updated_at"
end
CREATE TABLE maps (
id integer NOT NULL,
user_id integer,
map_type character varying(255),
name character varying(255),
description text,
map_width numeric,
map_height numeric,
created_at timestamp without time zone,
updated_at timestamp without time zone
);
Weirder
than
it
looks

9. Migrations
rails generate scaffold Map user_id:integer map_type:string
name:string description:text map_width:decimal
map_height:decimal
class CreateMaps < ActiveRecor
def change
create_table :maps do |t|
t.integer :user_id
t.string :map_type,
t.string :name,
t.text :description
t.decimal :map_width
t.decimal :map_height
!
t.timestamps
end
end
end
rake db:migrate && rails db:migrate RAILS_ENV=test

10. Heroku stack
•
Ruby-on-Rails front end
•
PostgreSQL preferred
•
Well documented
•
Free up to a reasonable point
•
Integrated with github
•
Lots of tools
•
Mostly works
•
https://www.heroku.com

11. Red
Green
Refactor
•
Agile & Stories
•
Examples & TDD (Testdriven development) over
APIs
•
MVC: Model/View/
Controller
•
Upgrades in RoR much
trickier than in PostgreSQL

12. Domain Specific Languages
•
•
PostgreSQL makes it
easy to hook existing
languages in: i.e.
Javascript as a server
language.
•
Gems versus packages.
About 30K gems! Of
widely varying quality.
•
YMMV
describe "home page" do
let!(:person)
{ FactoryGirl.create(:person) }
}
Ruby makes it easy to
write DSLs
before {
sign_in person
visit home_people_path(person)
}
it { should have_content(person.name)
it { should have_title(person.name) }
end

13. Long learning curves
•
Ruby-on-rails has a
lot of levels
•
Achieving rapport
with rails takes time
•
Help: railscasts,
stackoverflow, …
•
Grow little neurons,
grow (damn you!)

14. There’s a page for that
•
http://localhost:8081/phpPgAdmin/
•
http://guides.rubyonrails.org
•
http://api.rubyonrails.org
•
https://codeclimate.com
•
http://localhost:3000
•
https://github.com
•
http://ruby.railstutorial.org/book/ruby-on-rails-tutorial?
version=4.0
•
http://ruby-doc.com/docs/ProgrammingRuby/
•
…