example.rb

1.- rails jukebox -d mysql
2.- cd jukebox
3.- vi config/database.yml
4.- rake db:create:all
5.- ruby script/generate scaffold Artist name:string permalink:string albums_count:integer   
6.- ruby script/generate scaffold Album artist:references title:string permalink:string
7.- Edit your db/migrate 001_create_artists migration file to initialize the counter cache for artists_count and add the index for the permalink column.

  def self.up
    create_table :artists do |t|
      t.string :name
      t.string :permalink
      t.integer :albums_count, :default => 0

      t.timestamps
    end
    add_index :artists, :permalink
  end

8.- Similar process for the 002_create_albums migration file, we need to add the index for the permalink column.

  def self.up
    create_table :albums do |t|
      t.references :artist
      t.string :title
      t.string :permalink

      t.timestamps
    end
    add_index :albums, :permalink
  end

9.- rake db:migrate
10.- delete the public/index.html and update your config/routes.rb file with the default route to the artists controller:
map.root :controller => 'artists'

11.- Update the Model files for our asociations and allow counter_cache.

Edit the app/models/artist.rb
  has_many :albums

Edit the app/models/album.rb
  belongs_to :artist, :counter_cache => true

12.- Edit your Artists views and delete or comment part of the form to insert or edit Artists count since is a counter cache, 
we don't need to update manually

From the app/views/artists/new.html.erb and app/views/artists/edit.html.erb remove the Artists_count field...
<!--
  <p>
    <%= f.label :albums_count %><br />
    <%= f.text_field :albums_count %>
  </p>
  <p>
-->

13.- Lets prepare to for Permalink:
Add to your Artist model file app/model/artist.rb:

class Artist < ActiveRecord::Base
  has_many :albums

  def to_param
    permalink
  end

end
 *** REPEAT :: Add to_param function for the app/model/album.rb:

class Album < ActiveRecord::Base
  belongs_to :artist, :counter_cache => true

  def to_param
    permalink
  end
end

14.- To make this work lets update the Artist controller file app/controller/artists_controller.rb

Replace: Artist.find with Artist.find_by_permalink everywhere except the index action.

	*** Repeat to the Albums controller app/controller/albums_controller.rb:

Replace: Album.find with Album.find_by_permalink everywhere except the index action.

15.- Edit the New and Edit file for the Albums model: app/views/albums/new.html.erb

    <b>Artist</b><br />
    <%#= f.text_field :artist %>
    <%= collection_select(:album, :artist_id, Artist.find(:all), :id, :name, {:prompt => true}) %> 
  </p>

Now for the second file app/views/albums/edit.html.erb:
    <b>Artist</b><br />
    <%#= f.text_field :artist %>
    <%= collection_select(:album, :artist_id, Artist.find(:all), :id, :name, {:prompt => false}) %> 
  </p>
This change will retrieve the list of the current selected Artists in the select box.

16.- The last step some required validations for the appropiate operation of the application:
For the Artists: app/models/artist.rb

  validates_presence_of :name
  validates_presence_of :permalink

  validates_uniqueness_of :name
  validates_uniqueness_of :permalink

  attr_accessible :name, :permalink

For the Albums: app/models/album.rb:

  validates_presence_of :artist
  validates_presence_of :title
  validates_presence_of :permalink

  validates_uniqueness_of :title
  validates_uniqueness_of :permalink

17.- app/controllers/albums_controller.rb Sort by Artist....

    #@albums = Album.all
    @albums = Album.find(:all, :order => "Artist_id DESC")

app/controllers/artists_controller.rb Sort by Name....

    #@artists = Artist.all
    @artists = Artist.find(:all, :order => "Name ASC")

18.- Change the index/view to show properly...
app/views/albums/index.html.erb
    <td><%=h album.artist %></td>
    <td><%=h album.artist.name %></td>

19.- Quick Navigation

	<%= link_to 'Artists', artists_path %> |
	<%= link_to 'Albums', albums_path %>

20.- Add the Detail for Artist Albums...

List the albums for a particular artist:
app/views/artists/show.html.erb

<hr width="60%" size="1">

<table>
  <tr>
    <th>Artist</th>
    <th>Title</th>
    <th>Permalink</th>
  </tr>

<% @artist.albums.each do |album| %>
  <tr>
    <td><%=h album.artist.name %></td>
    <td><%=h album.title %></td>
    <td><%=h album.permalink %></td>
    <td><%= link_to 'Show', album %></td>
    <td><%= link_to 'Edit', edit_album_path(album) %></td>
    <td><%= link_to 'Destroy', album, :confirm => 'Are you sure?', :method => :delete %></td>
  </tr>
<% end %>
</table>
<hr width="60%" size="1">

21 BlackJack with Eric Berry Themes Plugin !!!

	http://github.com/cavneb/themes
./script/plugin install git://github.com/cavneb/themes.git
vi app/controllers/application_controller.rb
	layout 'themes'
:: Delete default controller application.

That's All folks go a head and start the web server...
ruby script\server

Feel free to navigate in your application at:
http://localhost:3000/artists
http://localhost:3000/albums