Ruby on Rails Tutorial, now with more 2.0.2!

My first Rails application was the ONLamp: Rolling with Ruby on Rails tutorial, since then Rails has come a long way but I find the beginner resources lacking still. The one thing I’ve learned along the way has been that sample code is invaluable, so today, in celebration of my company’s launch of our completely free online dating (and completely Rails) site Meeta.com, I offer present to you my version of the Rolling with Ruby on Rails tutorial on OSX.

As always, I am not a Rails genius, so my code may not be perfect; if I’ve done something wrong or there is a better, more Railsesque method please let me know. If you find this useful, leave me a comment, I like to know who is dropping in.

Enough of that. Let’s go!

Let’s start by creating our Rails application, if you’re looking for a tutorial on installing Rails check out the Rails wiki on installation.

From your command prompt, type the command “rails bookstore”. By default, Rails will use SQLite as the default database, if you want to use MySQL you will need to run “rails -d mysql bookstore”. This will create a “bookstore” subdirectory contanting a complete tree of folders and files for your Rails application. This is what you should see:

ng:Sites admin$ rails bookstore
      create
      create  app/controllers
      create  app/helpers
      create  app/models
      create  app/views/layouts
      create  config/environments
      create  config/initializers
      create  db
      create  doc
      create  lib
      create  lib/tasks
      create  log
      create  public/images
      create  public/javascripts
      create  public/stylesheets
      create  script/performance
      create  script/process
      create  test/fixtures
      create  test/functional
      create  test/integration
      create  test/mocks/development
      create  test/mocks/test
      create  test/unit
      create  vendor
      create  vendor/plugins
      create  tmp/sessions
      create  tmp/sockets
      create  tmp/cache
      create  tmp/pids
      create  Rakefile
      create  README
      create  app/controllers/application.rb
      create  app/helpers/application_helper.rb
      create  test/test_helper.rb
      create  config/database.yml
      create  config/routes.rb
      create  public/.htaccess
      create  config/initializers/inflections.rb
      create  config/initializers/mime_types.rb
      create  config/boot.rb
      create  config/environment.rb
      create  config/environments/production.rb
      create  config/environments/development.rb
      create  config/environments/test.rb
      create  script/about
      create  script/console
      create  script/destroy
      create  script/generate
      create  script/performance/benchmarker
      create  script/performance/profiler
      create  script/performance/request
      create  script/process/reaper
      create  script/process/spawner
      create  script/process/inspector
      create  script/runner
      create  script/server
      create  script/plugin
      create  public/dispatch.rb
      create  public/dispatch.cgi
      create  public/dispatch.fcgi
      create  public/404.html
      create  public/422.html
      create  public/500.html
      create  public/index.html
      create  public/favicon.ico
      create  public/robots.txt
      create  public/images/rails.png
      create  public/javascripts/prototype.js
      create  public/javascripts/effects.js
      create  public/javascripts/dragdrop.js
      create  public/javascripts/controls.js
      create  public/javascripts/application.js
      create  doc/README_FOR_APP
      create  log/server.log
      create  log/production.log
      create  log/development.log
      create  log/test.log
ng:Sites admin$

That’s a whole lot of files! I’m not going to get into details about the directory structure because I’m going to write another blog post about this next time. Very briefly, the bulk of the structure is as follows:

• app contains your application’s models, views, and controllers…the backbone of your app
• app/controllers contains all your controllers, these guys handle web requests
• app/helpers contains helper classes, these will help you clean up code allowing you to keep MVC (model, view, controller) code simple and neat
• app/models contains all your models, models are the gatekeepers to your database
• app/views contains all your views, these are display templates we will use to plug in data, which in turn is converted to the final HTML pages your users will see
• public holds all your publicily accessible files, think public_html

I bet you’re excited already…I was! Let’s fire up the server and see what’s going on. Run, “script/server”

ng:bookstore admin$ script/server
=> Booting Mongrel (use 'script/server webrick' to force WEBrick)
=> Rails application starting on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
** Ruby version is up-to-date; cgi_multipart_eof_fix was not loaded
** Starting Mongrel listening at 0.0.0.0:3000
** Starting Rails with development environment...
** Rails loaded.
** Loading any Rails specific GemPlugins
** Signals ready.  TERM => stop.  USR2 => restart.  INT => stop (no restart).
** Rails signals registered.  HUP => reload (without restart).  It might not work well.
** Mongrel available at 0.0.0.0:3000
** Use CTRL-C to stop.

Now, depending how your hosts are set up, visit your application in your browser:

• http://0.0.0.0:3000
• http://localhost:3000
• http:/127.0.0.1:3000

You should see the default Rails placeholder that looks like this:

You’ll notice this corresponds with the “public/index.html” file. Well, that’s not too exciting…let’s move on to creating your application. Delete the “index.html” file in your “public” directory, then shut down the web-server, and let’s really play ball.

Let’s think about a bookstore at a high level, and how they really work. A bookstore contains books with titles andthese books each belong to categories or genres. This is the foundation of our application. I’m going to show you how to create a working model, then I’ll explain it. By running the following command, you will create a scaffold for the books in your bookstore with a title and description. Run: “script/generate scaffold Book title:string description:text”

ng:bookstore admin$ script/generate scaffold Book title:string description:text
      exists  app/models/
      exists  app/controllers/
      exists  app/helpers/
      create  app/views/books
      exists  app/views/layouts/
      exists  test/functional/
      exists  test/unit/
      create  app/views/books/index.html.erb
      create  app/views/books/show.html.erb
      create  app/views/books/new.html.erb
      create  app/views/books/edit.html.erb
      create  app/views/layouts/books.html.erb
      create  public/stylesheets/scaffold.css
  dependency  model
      exists    app/models/
      exists    test/unit/
      exists    test/fixtures/
      create    app/models/book.rb
      create    test/unit/book_test.rb
      create    test/fixtures/books.yml
      create    db/migrate
      create    db/migrate/001_create_books.rb
      create  app/controllers/books_controller.rb
      create  test/functional/books_controller_test.rb
      create  app/helpers/books_helper.rb
       route  map.resources :books
ng:bookstore admin$

Okay, cool, but what is a scaffold? Think of buidings, when builders are working on a new building they put up scaffolds. This allows them to quickly build their building. As their project nears completion, they tear down the scaffolds. When you ran the “script/generate scaffold Book title:string description:text” command you asked Rails to create a scaffold for you. It provides you with a model, the necessary views, and a controller. These scaffolds allow you to quicky and rapidly develop an application, but should not be relied on in a production environment.

Let’s break down the command: “script/generate scaffold Book title:string description:text”

What you’ve done here is created a scaffold for your books, notice though the command says “Book”. ALL models in Rails are singular while views and controllers are plural. This was one of the points that confused me when I started using Rails, so pay attention! You’ll notice “title:string” and “description:text”, these are the corresponding field names and column types, even cooler is that Rails will automagically determine that your “string” is a VARCHAR or your text is TEXT. I used the examples title and description, because they are simple. These could have easily been “quantity:integer” or “isbn:string”.

Now that we’ve created a scaffold with a working model, views, and controller we need to physically create the database. Let’s do this now by running “rake db:migrate”

ng:bookstore admin$ rake db:migrate
(in /Users/admin/Sites/bookstore)
== 1 CreateBooks: migrating ===================================================
-- create_table(:books)
   -> 0.0035s
== 1 CreateBooks: migrated (0.0038s) ==========================================

ng:bookstore admin$

By running this command, you’ve asked rails to “migrate” your database using the “migrations” located in “db/migrate”. Pop in and take a look, but don’t freak out. I’ll explain those at another time. Boot up your server and navigate to your homepage, if you’ve forgotten how to do this just run, “script/server” and visit “http://localhost:3000″. You will likely encounter a “Routing error”, that’s okay though! Later, we will discuss routes, which allow you to control the URL structure.

Remember we created a scaffold for our model “Book”, well, the corresponding controller is located in “app/controllers/books_controller.rb”. Earlier I mentioned that the controller handles all the webrequests. By default, you can access a controller by it’s name, in this case, “books”. Change your browser’s URL to: “http://localhost:3000/books” and you should see this:

Well, what’s this…no books? Go ahead and add one! Before you get too excited, I want you to pay attention to the URL, notice that when you click “create” you are taken to “http://localhost:3000/books/new” this URL will correspond very closely with your application’s internal workings. .After you add a book, you should see a quick summary of the book you’ve inputted into the database; here’s one that I’ve added:

Click the back button, and return to the index.

Wasn’t that simple? You have a basic bookstore where you can create, edit, update, and destroy books from a working database! Take some time to reread this tutorial and play with the application’s internal workings, get familiar with everything here because I will use it as a foundation from this point forward.

If you need the source code, you can download it here.

Was this helpful, do you have questions, or do you just want to bullshit? Leave me a comment! Feel like donating to my beer fund?

Check out part two, “Basic Rail’s routing and a journey into Views, and Controllers“!