Transcraft Trading Limited

Off the Rails ?

"Give me a place to stand and with a lever I will move the whole world."

With the right tools, even an average guy can fix his own blocked drain. You do not go into battle an elite airborne division armed with just a spear and two coconuts ! In the same light, to build this world class application, we first need the building blocks. In our case, they are Ruby, Gem and Rails, in that order.

Ruby

Mandrake normally comes with Ruby pre-installed in a RPM package. My v9.2 has ruby-1.8.0-4mdk installed. This version is no good for Rails and Gem (the Ruby equivalent of RPM, the de facto Red Hat package installation and management utility). I found this out after installing Gem, thinking I already had Ruby. Maybe I should have read the instructions first :-(. Anyway, the first thing you will have to do is download Ruby 1.8.3, build and install it.


  $ wget ftp://ftp.ruby-lang.org/pub/ruby/ruby-1.8.3.tar.gz

  --19:20:05-- ftp://ftp.ruby-lang.org/pub/ruby/ruby-1.8.3.tar.gz

  => `ruby-1.8.3.tar.gz.1'

  Resolving ftp.ruby-lang.org... done.

  Connecting to ftp.ruby-lang.org[210.163.138.100]:21... connected.

  Logging in as anonymous ... Logged in!

  ==> SYST ... done. ==> PWD ... done.

  ==> TYPE I ... done. ==> CWD /pub/ruby ... done.

  ==> PASV ... done. ==> RETR ruby-1.8.3.tar.gz ... done.

  Length: 4,227,276 (unauthoritative)

  

  100%[====================================>] 4,227,276 21.49K/s ETA 00:00

  

  19:23:27 (21.49 KB/s) - `ruby-1.8.3.tar.gz.1' saved [4227276]
$ gzip -dc
  ruby-1.8.3.tar.gz | tar xvf -

    $ cd ruby-1.8.3

    $ ./configure

    $ make

    $ sudo make install

This will install ruby under /usr/local/bin and all Ruby libraries under /usr/local/lib/ruby.

RubyGem

The next thing to install is gem. According to the Ruby on Rails download website, all I need to do is to get hold of rubygems-0.8.11 or higher. Nothing simpler. So I clicked on this link and was taken to the Rubyforge repository, where I downloaded rubygems-0.8.11.tgz.


  $ gzip -dc rubygems-0.8.11.tgz | tar xvf -
$ cd rubygems-0.8.11

  ./configure

    $ make

    $ sudo make install

Looking good. The next thing is Rails.

Rails


  $ gem install rails --source http://gems.rubyonrails.com
  --include-dependencies
  
Attempting local installation of 'rails'

  Local gem file not found: rails*.gem

  Attempting remote installation of 'rails'

  Updating Gem source index for: http://gems.rubyforge.org

  Successfully installed rails-0.14.3
$ rails /home/david/myapp

  /usr/local/lib/ruby/site_ruby/1.8/rubygems/source_index.rb:3:in `require': no
  such file to load -- forwardable (LoadError)

  from /usr/local/lib/ruby/site_ruby/1.8/rubygems/source_index.rb:3

  from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:395

  from /usr/local/bin/rails:9

Oops, what went wrong here ? rails was installed successfully, was it not ? why do I get this error when I invoke rails ? According to the instructions, all I need to do is run "rails /complete/path/to/new/railsapp" and magic and fireworks should happen. Well, after about a day scratching my head, turning on debug, looking at stack trace etc. I finally discovered the problem is to do with the last step I did. When I installed ruby as root, for some reason the files were all written out into /usr/local/lib/ruby without world read permissions


  $ ls -lrt /usr/local/lib/ruby/1.8

  drwxr-xr-x 2 root root 4096 Nov 28 22:26 bigdecimal/

  -rw-r----- 1 root root 60 Nov 28 23:06 tkwinpkg.rb

  -rw-r----- 1 root root 69 Nov 28 23:06 tkvirtevent.rb

  -rw-r----- 1 root root 54 Nov 28 23:06 tktext.rb

  -rw-r----- 1 root root 69 Nov 28 23:06 tkscrollbox.rb

  -rw-r----- 1 root root 127659 Nov 28 23:06 tk.rb

  -rw-r----- 1 root root 63 Nov 28 23:06 tkpalette.rb

  -rw-r----- 1 root root 66 Nov 28 23:06 tkmngfocus.rb

OK, so you say, serves him right. It is his own fault for having crazy permissions. I agree. But look at the error trace above, would I have been able to determine that is the problem ? I am saying this because this is the general theme I find in the rest of the installation, in that the ruby stack traces most of the time do not seem to have any correlation with the actual system error that will help me zero in on the problem. Searching in Google does not help that much either because whichever way you go seems to take you to one of the few main Rails sites, with the procedures all pointing to a standard Windows installation. At least, I did discover that whenever you get an error saying 'constant_missing', then it seems to indicate the equivalent ClassNotFoundException in Java i.e. Ruby could not locate a particular resource. The class name it is complaining about should be converted into lower case with embedded underscores in order to locate the actual physical file it is looking for e.g. ActiveRecord translates to active_record.rb.


  $ rails myapp 

  create 

  create app/controllers

  create app/helpers

  create app/models

  create app/views/layouts

  create config/environments

  create components

  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/mocks/development

  create test/mocks/test

  create test/unit

  create vendor

  create vendor/plugins

  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/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/breakpointer

  create script/console

  create script/destroy

  create script/generate

  create script/performance/benchmarker

  create script/performance/profiler

  create script/process/reaper

  create script/process/spawner

  create script/process/spinner

  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/500.html

  create public/index.html

  create public/favicon.ico

  create public/robots.txt

  create public/javascripts/prototype.js

  create public/javascripts/effects.js

  create public/javascripts/dragdrop.js

  create public/javascripts/controls.js

  create doc/README_FOR_APP

  create log/server.log

  create log/production.log

  create log/development.log

  create log/test.log

Caramba ! My first Rails application. Well, at least, the skeleton for my first Rails application any way. Alas, I rejoice too soon, the rest of the journey is fraud with fire breathing dragons, green skin ogres, and funny shaped Trolls. Read on.

Next page A gold medal is a wonderful thing, but if you're not enough without the medal, you'll never be enough with it.

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