Ruby on Rails

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Revision as of 22:10, 20 January 2009 by Phil (Talk | contribs)
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This is valid for Rails 2.2.2, the version i'm using currently. May be valid for other versions.


Fast commands

  • Help yourself, use BORT for application baseline


ruby script/generate scaffold Project name:string description:text
ruby script/generate migration AddOwnerToProject
rake db:migrate


rake routes



  1. Install or
  2. Look in log/development.log
  3. Add "debugger" somewhere in the controller
  4. Relaunch the server using "ruby script/server --debugger"
    1. now commands can be typed like "list", "up", "irb" (for an Interactive Ruby session) or "cont"
    2. Remember the name of the top level object is "self" so printing something like "p self" can be useful


Usually with:

ruby script/server

You can do a simple command to install mongrel instead:

gem install mongrel

To install.... then check


rake dbconsole


rake console





gem install <gemname>

if it breaks, try to do:

gem install

if it still breaks, try to do:

require 'rubygems'
gem 'myproblemgem', '1.0.0'

then look at the problem.


for example this session shows that the "echoe" gem is not installed. When running script/server:

/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
Missing these required gems:
  capistrano-ext  = 1.2.1

You're running:
  ruby at /usr/local/bin/ruby
  rubygems 1.2.0 at /usr/local/lib/ruby/gems/1.8

Run `rake gems:install` to install the missing gems.

well... indeed Captistrano-ext IS installed:

$ ls -ald /usr/local/lib/ruby/gems/1.8/gems/cap*
drwxr-xr-x   12 root  wheel  408 Jan 20 12:11 /usr/local/lib/ruby/gems/1.8/gems/capistrano-2.5.3
drwxr-xr-x    9 root  wheel  306 Jan 20 13:00 /usr/local/lib/ruby/gems/1.8/gems/capistrano-ext-1.2.1

but running the code with irb gives more details:

$ irb
>> require 'rubygems'
=> false
>> gem 'capistrano-ext', '1.2.1'
Gem::LoadError: Could not find RubyGem echoe (>= 0)

        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:578:in `report_activate_error'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:134:in `activate'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:158:in `activate'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `each'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `activate'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:158:in `activate'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `each'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `activate'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:158:in `activate'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `each'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `activate'
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:49:in `gem'
        from (irb):2

So a simple:

# gem install echoe
Successfully installed echoe-3.0.2
1 gem installed
Installing ri documentation for echoe-3.0.2...
Installing RDoc documentation for echoe-3.0.2...

fixed the problem... well... you get the idea: there's a broken dependency in captistrano-ext for echoe....

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