forked from pifty/tutes-dump
191 lines
7.2 KiB
HTML
191 lines
7.2 KiB
HTML
<html><head>
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<title>Building a Basic Ruby on Rails Application</title>
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<style>
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li {
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padding-top: 1em;
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}
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</style>
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</head><body>
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<h1>Building a Basic Ruby on Rails Application</h1>
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<ul>
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<li><b>Part I: Getting Started</b><ul>
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<li><a href="#introduction">Introduction</a></li>
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<li><a href="#creating_project">Creating a Rails Project</a></li>
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<li><a href="#building_model">Building The Data Model</a></li>
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<li><a href="#quick_demo">A Quick Demonstration!</a></li>
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</ul></li>
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<li><b>Part II: Layout and Design</b></li>
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<li><b>Part III: Making it Better</b></li>
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<li><b>Appendix</b><ul>
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<li><a href="#appendix_sdf_utils">Appendix A: SDF Utility Scripts</a></li>
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<li><a href="#appendix_database_conf">Appendix B: Configuring A Database</a></li>
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</ul></li>
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</ul>
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<hr />
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<h2>Introduction</h2>
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<p>[ To Be Written ]</p>
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<a name="creating_project" /><h2>Creating a Rails Project</h2>
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<p>All rails applications reside in their own directory tree. This tree is
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automatically generated by the '<code>rails</code>' command ( '<code>man rails
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</code>' for more information ). To create our project's directory structure,
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execute the following:</p>
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<code>
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(alterego@sverige)# rails ~/html/bookmarks --database=sqlite3<br />
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(alterego@sverige)# ln -s bookmarks ~/html/rails<br />
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(alterego@sverige)# cd ~/html/rails
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</code>
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<p>The first command creates our project's directory tree under the
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'<code>~/html/bookmarks</code>' directory. Then we create a symlink from this
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directory, to '<code>~/html/rails</code>' so that the SDF utility scripts will
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be able to find, and work with this project. ( <a href="#appendix_sdf_utils">
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More info</a> )</p>
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<p>The '<code>--database=sqlite3</code>' argument to the '<code>rails</code>'
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executable, informs Rails to configure the new project to use an SQLite3
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database backend. If you have 'dba' membership then you can use MySQL as your
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backend by substituting '<code>sqlite3</code>' with '<code>mysql</code>'. This
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tutorial will however focus in using SQLite3 as it is available to all MetaARPA
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members. If you are going to use MySQL as your database backend, then you'll
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have to read <a href="#appendix_database_conf">this</a> in order to configure
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your backend properly.</p>
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<p>The final command changes your working directory to your new projects' root.
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The rest of the commands in this tutorial rely on you being at this location in
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order to execute correctly.</p>
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<a name="building_model" /><h2>Building The Data Model</h2>
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<p>Now we are sitting in our nice new Rails project's root directory, we can
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start building our application. The most important thing in any database driven
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application like this one, is the data model. It specifies what data our
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application interacts with, and <em>how</em> we interact with it.</p>
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<p>In this application, we only have one data type, that is a 'Link', this link
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must have a name, some descriptive information and the target URI. Normally at
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this stage you'd have to roll-up your sleaves and write one of those fugly SQL
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statements to create your table. Not us, Rails has cunningly abstracted database
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interaction for us, so no more SQL! In order to create our mode we must run
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this command:</p>
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<code>
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(alterego@sverige)# ruby script/generate model link
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</code>
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<p>This command line executes the Ruby script, '<code>script/generate</code>'.
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The '<code>generate</code>' script is extremely useful, it automates the process
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of creating files to add specific functionality to our applications. You can
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tell what operations a '<code>generate</code>' command has performed by reading
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it's output. This command created the two files required to create our 'Link'
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model.</p>
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<p>Next we need to edit the '<code>db/migrate/001_create_links.rb</code>' file.
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Files located under the '<code>db/migrate</code>' directory are used to perform
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revision changes on your project's database. This file will allow us to specify
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our databases table without the need for any SQL, and, if required, roll our
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database back to before this migration occured.</p>
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<h3>Edit '<code>db/migrate/001_create_links.rb</code>'</h3>
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<pre>
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class CreateLinks < ActiveRecord::Migration
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def self.up
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create_table :links do |t|
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t.column :name, :string
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t.column :info, :string
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t.column :url, :string
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end
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end
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def self.down
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drop_table :links
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end
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end
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</pre>
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<p>Now we've specified our '<code>links</code>' table's structure. We have to
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commit the revision in order to create the table. To do this execute the
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following:</p>
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<code>
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(alterego@sverige)# rake db:migrate
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</code>
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<p>Going into the details of this command is way outside the scope of this
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document, I wouldn't have used it in this tutorial if it wasn't for it being
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such an easy way to generate a database across different backends.</p>
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<a name="quick_demo" />
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<h2>A Quick Demonstration!</h2>
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<p>Before we move on to defining the application controller, I thought I would
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try and impress you with Rails magic. The next two commands will allow you to
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list, view, edit and delete items from your database through your web browser:
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</p>
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<code>
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(alterego@sverige)# ruby script/generate scaffold link<br />
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(alterego@sverige)# ruby script/server -p `id -u`
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</code>
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<p>Right, those two commands did quite a bit. The first one generated a basic
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set of HTML templates and application logic. The second command started a
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web server, written in Ruby, running on a port that was specified from your
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userid. You'll notice on the second line of output from the '<code>server
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</code>' script, the address that it has bound itself too, along with the port
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number ( your user id ) it is running on in standard URI format.</p>
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<p>So, open up a web browser, and point it to
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'<code>http://sverige.freeshell.org:[ YOUR USER ID ]</code>' substituting your
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user id. Your browser should open 'Ruby on Rails: Welcome aboard' page. This
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just indicates that the Rails environment and server are running. Now, go back
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to your browsers' address bar, and append '<code>/links</code>' after your user
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id. Your browser should now show a rather rubbish looking list view, with no
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elements.</p>
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<p>At this point it will probably be a good idea to play around and add some
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items as we'll need them for the next sections. Besides, I need to make myself a
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drink ...</p>
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<h2 style="text-align: center;">To Be Continued ...</h2>
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<hr />
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<a name="appendix_sdf_utils" /><h2>Appendix A: SDF Utility Scripts</h2>
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<p>There are two utility scripts written specifically for Rails applications
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on SDF. The first 'ror' toggles whether the Rails project under '<code>
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~/html/rails</code>' has it's server started when the syste boots. The second
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script 'railsctl', is start/stop daemon, which starts or stops the Rails
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project located in the standard SDF project location.</p>
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<p>As you may want to play with multiple Rails projects, it doesn't really
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matter where you put them, or what you call them. But if you plan on using the SDF utility scripts, which is a good idea if you want to host your project,
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then it's probably a good idea to symlink your current project directory to
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'<code>~/html/rails</code>'</p>
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<a name="appendix_database_conf" /><h2>Appendix B: Configuring A Database</h2>
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<p>[ To Be Written ]</p>
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<div style="font-size: 8pt;">
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$Id: Rails_Basic_Application.html,v 1.2 2006/12/31 14:27:54 alterego Exp $
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</div></body></html>
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