RoR Hello From Rails App

Let’s create our first Rails app.

(In the previous section, there were separate boxes to show what to type and what the output looks like. Now that we are all at least sophmore Rails programmers, we will dispense with that convention and just show what you type interspersed with the output.)

Creating An Empty Rails Application

Rails will create an empty application for us:

C:\>mkdir \rails
C:\>cd \rails
C:\rails>rails demo
    create
    create  app/controllers
    create  app/helpers
    create  app/models
    ...
    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
C:\rails>

This won’t do anything, but sets up the files and directories we need.

“Hello from Rails” Application

Now let’s create a simple “Hello from Rails” application. Type:

C:\rails>cd \rails\demo
C:\rails\demo>ruby script\generate controller Say
    exists  app/controllers

    exists  app/helpers

    create  app/views/say
    exists  test/functional

    create  app/controllers/say_controller.rb
    create  test/functional/say_controller_test.rb
    create  app/helpers/say_helper.rb
C:\rails\demo>

Now edit the app\controllers\say_controller.rb file to look like this:

class SayController < ApplicationController
  def hello
  end
end

And create app\views\say\hello.rhtml:

<html>
  <head>
    <title>Hello Rails</title>
  </head>
  <body>
    <h1>Hello from Rails!</h1>
  </body>
</html>

Now start the Webrick server:

C:\rails\demo>ruby script\server
  => Booting WEBrick...
  => Rails application started on http://0.0.0.0:3000
  => Ctrl-C to shutdown server; call with --help for options
  [2006-07-11 21:13:31] INFO  WEBrick 1.3.1
  [2006-07-11 21:13:31] INFO  ruby 1.8.4 (2005-12-24) [i386-mswin32]
  [2006-07-11 21:13:31] INFO  WEBrick::HTTPServer#start: pid=2840 port=3000

And open your new Rails application:

http://localhost:3000/say/hello

Impressed? I am!

— – –

(This example taken from the fantastic Rails book Agile Web Development with Rails . Get a few copies so you can give some to your friends!)

Directory Structure

Let’s take a few minutes to look at the directory structure of this Rails application. Remember, that Rails emphasizes “Convention Over Configuration” so all Rails apps you will run into will have this same structure.

App

The app directory is where all your code goes. Inside are four directories: controllers, models, views and helpers. In controllers there is one file for every controller; in the other directories, there will be a subdirectory corresponding to each controller.

  • Views: The stuff you see on the screen
  • Helpers: The place to put the complicated screen code so it doesn’t clutter up the views
  • Models: The logic of the application that doesn’t care how it looks
  • Controllers: The glue that ties all this together

Config

The config directory is where, umm, the config files go. Besides the app directory, this is the only other directory that you will need to mess with to get your Rails application running.

DB

The db directory is where you keep your database schema files and the migration files. Migrations are a great way to keep the database up-to-date and in sync with the Rails code, no matter what database changes you make.

Public

The public directory is the only one that the web server sees. It contains the dispatch.cgi file (which is how the Rails app gets started) and also files served up directly to the web server. So if you need to put images on your Rails pages, or edit the stylesheet, this is where you do it.

Other Directories

The other directories are pretty much self explanatory, and we won’t need them for this tutorial

Revised on August 29, 2006 20:40:49 by Max Dunn (69.226.247.80)