A presentation detailing building a Rails shopping cart from scratch

1. Intro to Ruby on Rails Jason Noble http://jasonnoble.org Alan Hecht http://alanhecht.me

2. Slides are available http://slideshare.net/jasonjnoble/ Intro to Rails Give Camp Atlanta Finished code is also available https://github.com/jasonnoble/givecampatl-rails-demo

4. History Initial Release July 2004 Written by David Heinemeier Hansson Rails 3.0 released August 29, 2010

5. Technical Overview Model-View-Controller (MVC) architecture Includes scaffolding to automatically construct the models and views needed for a basic site Includes WEBrick, a simple Ruby web server Includes Prototype and Script.aculo.us JavaScript libraries for Ajax RESTful web services used instead of SOAP Handles HTML and XML output out of the box

6. Framework Structure ActiveRecord – Object relational mapping system for database access ActiveResource -- Web Services ActionPack ActiveSupport ActionMailer Lots of plugins available

7. Philosophy Convention over Configuration Decreases decisions that developers need to make By doing things the “standard” way it just works Don’t Repeat yourself (DRY) Every piece of code has a single, unambiguous authoritative representation within a system Modifying any single element does not change other logically-unrelated elements Use methods and subroutines to abstract out pieces of code called in multiple places

8. Installing Install Ruby and RubyGems Gems are a Ruby package format gem install rails Rails works with SQLite out of the box MySQL, PostgreSQL, Oracle, MS SQL gems available

9. Installing Rails Windows http://pragmaticstudio.com/blog/2010/9/23/install-rails-ruby-windows OS X http://pragmaticstudio.com/blog/2010/9/23/install-rails-ruby-mac Linux Most of http://pragmaticstudio.com/blog/2010/9/23/install-rails-ruby-mac will work

10. Let’s build a shopping cart rails new demo_app vi demo_app/.rvmrc rvm –create use 1.9.2@rails3 cd demo_app rails server http://localhost:3000 gitinit . git add . git commit –m ‘Initial rails app’

11. Push App to Heroku vi Gemfile Add “gem heroku” line bundle install heroku create git push –u heroku master heroku open

12. Product Scaffolding Add a CRUD (create, read, update, delete) interface rails generate scaffold Product title:stringdescription:textimage_url:stringprice:decimal creates db/migrate/20110108190442_create_products.rb

13. db/migrate/2011010819_create_products.rb Filename is date/time specific, so yours may differ Adding precision and scale to price field rake db:migrate http://localhost:3000/products

14. Modifying the view app/views/products/_form.html.erb Views are dynamically rendered, so reloading in your browser will show your updates

15. Seeding your DB with data db/seeds.rb Executes Ruby code to pre-populate your database Good way to start with sample data rake db:seed Runs the ruby code

16. Update Products View app/views/products/index.html.erb

17. Push to Heroku git add . git commit –m ‘Products scaffold’ git push heroku heroku rake db:migrate heroku rake db:seed heroku open add a /products to the URL

18. Data Validation Rails has data validation built into the model app/models/product.rb

19. Data Validation (cont.)

20. Rails Testing rake test Runs all the built in Rails tests Prints Failures as it finds them, but continues

21. Functional Tests Tests Controller actions test/functional/products_controller_test.rb

22. Unit Tests Tests Model methods/attributes/validations test/unit/product_test.rb

23. Push to Heroku git add . git commit –m ‘Added validation’ git push heroku

24. Store Front rails generate controller store index http://localhost:3000/store/index gitrm public/index.html config/routes.rb http://localhost:3000/

25. Store Controller Modify store controller to pull products from the database app/controllers/store_controller.rb

26. View file changes app/views/store/index.html.erb

27. Application Layout app/views/layouts/application.html.erb

28. Updated view

29. Customer wants books alphabatized app/models/product.rb

30. Store Functional Test test/functional/store_controller_test.rb

31. Push to Heroku git add . git commit –m ‘Store scaffold’ git push heroku heroku open

32. Cart Scaffold rails generate scaffold cart rake db:migrate

33. Modify Application Controller app/controller/application_controller.rb

34. LineItems scaffold rails generate scaffold line_itemproduct_id:integercart_id:integerquantity:integer

35. Update Cart model app/models/cart.rb

36. Update LineItem Model app/models/line_item.rb

37. Update Product model app/models/product.rb

38. Add to Cart button app/views/store/index.html.erb

39. LineItems controller app/controllers/line_items_controller.rb

40. Carts View app/views/carts/show.html.erb

41. Carts Controller app/controller/carts_controller.rb

42. Update Heroku git add . git commit –m ‘Cart updated’ git push heroku heroku open

43. Further Reading Agile Web Development with Rails http://pragprog.com/titles/rails4/agile-web-development-with-rails http://rubyonrails.org http://railsforzombies.org/ http://tryruby.org/ http://rubykoans.com/