RoR: Railroad plugin with Rails 2.3.5 on Windows error

While looking for a tool that’d help me to generate the database schema diagram, I’ve found RailRoad Ruby gem. However, it was not working with my Rails 2.3.5 + Ruby 1.8.7 on Windows. While running railroad in command line, I was getting an error:

 c:/Ruby/lib/ruby/gems/1.8/gems/railroad-0.5.5/lib/railroad/app_diagram.rb:54:in 'reopen': No such file or directory - /dev/null (Errno::ENOENT)

(...)

This seemed to me as an error similar to RoR: plugin install from GIT repository in Windows error. And luckily it was!

Solution

The soultion is as follows:

1. Go to %ruby_installation_directory\lib\ruby\gems\1.8\gems\railroad-0.5.5\lib\railroad\ and open app_diagram.rb in a text editor.
   (%ruby_installation_directory is c:\Rails by default)
2. Around line 54 find:

   STDOUT.reopen(PLATFORM =~ /mswin/ ? "NUL" : "/dev/null")

   and change it to:

   #STDOUT.reopen(PLATFORM =~ /mswin/ ? "NUL" : "/dev/null")
   	STDOUT.reopen('NUL:')

3. Open controllers_diagram.rb in the same directory with a text editor.
4. Around line 39 find:

   require "app/controllers/application.rb" 

   and change it to:

   require "app/controllers/application_controller.rb" 

5. That’s all! Now you can create for example your Rails project models schema (having Graphvis installed) just typing in command line:

   railroad -a -i -M | dot -Tpng > models.png

Create tasks

To automate the process of creating schemes, you can create Rails task. In your rails_project_dir/Libs/tasks create diagrams.rake and copy the text:

namespace :doc do
  namespace :diagram do
    task :models do
      sh "railroad -a -i -M | dot -Tpng > doc/models.png"
      sh "railroad -i -l -a -m -M | dot -Tsvg doc/models.svg"
    end

    task :controllers do
      sh "railroad -i -l -C | neato -Tsvg > doc/controllers.svg"
    end
  end

  task :diagrams => %w(diagram:models diagram:controllers)

end

Now you can run the task by typing in console: rake doc:diagrams to generate all diagrams (for models an controllers) or rake doc:diagram:models to generate diagram for models only.

Due to the information on RailsRoad Docs, there is a bug in Graphvis while crating svg graphic. There is a simple way to correct it (citation from RailsRoad Docs):

Important: There is a bug in Graphviz tools when generatingSVG files that cause a text overflow. You can solve this problem editing (with a text editor, not a graphical SVG editor) the file and replacing around line 12 „font-size:14.00;” by „font-size:11.00;„, or by issuing the following command (see „man sed„):

sed -i 's/font-size:14.00/font-size:11.00/g' file.svg

Note: For viewing and editing SVG there is an excellent opensource tool called Inkscape (similar to Adobe Illustrator.) For DOTprocessing you can also use Omnigraffle (on Mac OS X).