CS142

2-13-09 Section Notes

Project 6 - Intro to Ruby on Rails - http://crypto.stanford.edu/cs142/projects/6/project6.html

MySQL

• To administer your database, we recommend MySQL Administrator and MySQL Query Browser (http://dev.mysql.com/downloads/gui-tools/5.0.html)
• Use MySQL Administrator for modifying data schema (the way the data's structured)
• Use MySQL Query Browser to get/modify the data itself
• Alternatives include:
  • phpMyAdmin (cross platform - http://www.phpmyadmin.net/home_page/index.php)
  • Sequel Pro (mac only - http://www.sequelpro.com/)

Rails Overview

• Most important folders in a rails project:
  • app/ - contains Model, View, and Controller files you'll be creating/modifying
  • app/models/ - folder for data classes for your application. Facilitates database interaction and also contains data you want to keep around for a single session but don't want to write to your database.
  • app/controllers/ - each file in this folder represents a controller object. In each of these controller files are action definitions which are exectued when the controller and action are parsed from a URL.
  • app/views/ - show view files
  • public - folder webserver is run out of. Contains images, stylesheets, and javascript directories.
  • IMPORTANT: Absolute file paths in your HTML have the public folder as root. So in project 6, "/images/indy.jpg" resolves to project6/public/images/indy.jpg.


• Rails URL Loading Example:
  1. URL = http://localhost.com:3000/halo/allPlayers
  2. controller = "halo", action = "allPlayers"
  3. allPlayers function in app/controllers/halo_controller.rb is then executed
  4. the view for that action is executed, app/views/halo/allPlayers.html.erb
  5. the HTML files generated by the allPlayers view are then executed in the "public" directory so all absolute paths have a runtime root = "public"

Starting/Stopping the Server

• Starting a server:
  • mac/linux: script/server
  • windows: ruby script/server


• Testing your server:
• http://localhost:3000 - should look like this: http://barkingiguana.com/images/rails-default-index.png


• Troubleshooting:
• Restart your server - solves lots of problems

Creating/Destroying a Controller

• Create a halo controller and allPlayers action:
  • mac/linux: script/generate controller halo allPlayers
  • windows: ruby script/generate controller halo allPlayers


• Testing your controller + action:
• http://localhost:3000/halo/allPlayers
• format: http://server:port/controller/action


• To delete the halo controller (and files created by previous "script/generate" call):
• mac/linux: script/destroy controller halo
• windows: ruby script/destroy controller halo
• NOTE: this deletes the controller AND all the actions in that controller
• NOTE: this also deletes the views generated for the controller

Example - Halo Stats

• MySQL Table Schema:



Players		# Players table in database
	id
	name
	character_class	# spartan or elite
Games		# Games table in database
	id
	player_id	# player these game stats are for
	kills	# total kills in the game
	deaths	# total deaths in the game
	level	# name of the game level (eg, Zanzibar)
	game_type	# name of the game type (eg, Free For All)



• app/models/player.rb:

  class Player < ActiveRecord::Base
      has_many :games
  end
  



• app/models/game.rb:

  class Game < ActiveRecord::Base
      belongs_to :player
  end
  



• app/controllers/halo_controller.rb:

  class HaloController < ApplicationController
    def allPlayers
      @players = Player.find(:all);
    end
  
    def player
      @player = Player.find(params[:id]);
    end
  end
  

• app/views/halo/allPlayers.html.erb:

  
  <!-- NOTE: Your code MUST validate, even though this sample code doesn't -->
  
  <h1>All Halo Players</h1>
  
  <ul>
  	<% @players.each do |player| %>
  	<li><%= link_to h(player.name), :action => "player", :id => player.id %></li>
  	<% end %>
  </ul>
  

• app/views/halo/player.html.erb:

  <!-- NOTE: Your code MUST validate, even though this sample code doesn't -->
  
  <pre>
  <h3>Name:</h3> <%= h(@player.name) %>
  <h3>Class:</h3> <%= h(@player.character_class) %>
  <h3>Inverted:</h3> <%= h(@player.inverted) %>
  
  <h3>Games</h3>
  <table>
  	<tr>
  		<th>Level</th>
  		<th>Game Type</th>
  		<th>Kills</th>
  		<th>Deaths</th>
  	</tr>
  
  	<% @player.games.each do |game| %>
  	<tr>
  		<td><%= h(game.level) %></td>
  		<td><%= h(game.game_type) %></td>
  		<td><%= h(game.kills) %></td>
  		<td><%= h(game.deaths) %></td>
  	</tr>
  	<% end %>
  
  </table>
  

• NOTES:
  • Difference between <% and <%=
    • <% : execute code, produces no HTML
    • <%= : substitution, output of command inserted in HTML
  • h():
    • escapes HTML text
    • protects against XSS
  • ()'s are not required:
    • You can use either syntax:

      • h(player.name)

      • h player.name

  • ;'s are not required
    • You can use either syntax:

      • i = i + 1

      • i = i + 1;

Questions?

1. Double-check the writeup - http://crypto.stanford.edu/cs142/projects/6/project6.html)
2. Check then post to the newsgroup - su.class.cs142
3. Email the TA's - cs142@cs.stanford.edu