Ruby on Rails 3/4/5 model and controller UML class diagram generator. (`brew/port/apt-get install graphviz` before use!)
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Minor description change for rake tasks
Latest commit ec476b9 Mar 21, 2018


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RailRoady generates Rails 3/4/5 model (ActiveRecord, Mongoid, Datamapper) and controller UML diagrams as cross-platform .svg files, as well as in the DOT language.

Code is based on the original "railroad" gem, patched and maintained over the years. Lineage can be traced via GitHub.

I (Preston Lee) am not trying to hijack Peter Hoeg or Javier's project, but rather create a dedicated, lean gem that can be used without major issue on Rails projects. Rails v2 is not supported.

System Requirements

You MUST have the the following utilities available at the command line.

  • dot and neato.

  • sed, which should already be available on all sane UNIX systems.

Mac users

Brew users can install via:

brew install graphviz

MacPorts users can install in via

sudo port install graphviz

Ubuntu users

Ubuntu users can install in via

sudo apt-get install graphviz


The easiest (and recommend) usage is to include railroady as a development dependency with your Rails 3 Gemfile, like so...

group :development, :test do
    gem 'railroady'

...and then run the master rake task...

rake diagram:all

This should generate four doc/*.svg files that can be opened in (most) web browsers as well as dedicated document viewers supporting the Scalable Vector Graphics format.

Support for Engines

Generate diagram for models and controllers including those in the engines.

rake diagram:all_with_engines

Alternate Usage

Alternatively, you may run the 'railroady' command-line program at the Rails application's root directory. You can redirect its output to a .dot file or pipe it to the dot or neato utilities to produce a graphic. Model diagrams are intended to be processed using dot and controller diagrams are best processed using neato.

railroady [options] command


Common options:
  	-b, --brief                      Generate compact diagram
                                     (no attributes nor methods)
  	-s, --specify file1[,fileN]      Specify only given files
  	-e, --exclude file1[,fileN]      Exclude given files
  	-i, --inheritance                Include inheritance relations
  	-l, --label                      Add a label with diagram information
                                     (type, date, migration, version)
  	-o, --output FILE                Write diagram to file FILE
  	-r, --root PATH                  Set PATH as the application root
  	-v, --verbose                    Enable verbose output
                                     (produce messages to STDOUT)
  	-x, --xmi                        Produce XMI instead of DOT
                                     (for UML tools)
    --alphabetize                Sort methods alphabetically

Models diagram options:
  	-a, --all                        Include all models
                                     (not only ActiveRecord::Base derived)
      	--show-belongs_to            Show belongs_to associations
      	--hide-through               Hide through associations
      	--all-columns                Show all columns (not just content columns)
      	--hide-magic                 Hide magic field names
      	--hide-types                 Hide attributes type
  	-j, --join                       Concentrate edges
  	-m, --modules                    Include modules
  	-p, --plugins-models             Include plugins models
  	-z, --engine-models              Include engine models
      	--include-concerns           Include models in concerns subdirectory
  	-t, --transitive                 Include transitive associations
                                   	(through inheritance)

Controllers diagram options:
      	--hide-public                Hide public methods
      	--hide-protected             Hide protected methods
      	--hide-private               Hide private methods
      	--engine-controllers         Include engine controllers

Other options:
  	-h, --help                       Show this message
      	--version                    Show version and copyright

  	-c, --config FILE                File to load environment (defaults to config/environment)


You must supply one of these:

-M, --models                     Generate models diagram
-C, --controllers                Generate controllers diagram
-A, --aasm                       Generate "acts as state machine" diagram


railroady -o -M
  Produces a models diagram to the file ''
railroady -a -i -o -M
  Models diagram with all classes showing inheritance relations
railroady -M | dot -Tsvg > models.svg
  Model diagram in SVG format
railroady -C | neato -Tpng > controllers.png
  Controller diagram in PNG format
railroady -h
  Shows usage help

Processing DOT files

To produce a PNG image from model diagram generated by RailRoady you can issue the following command:

dot -Tpng > models.png

If you want to do the same with a controller diagram, use neato instead of dot:

neato -Tpng > controllers.png

If you want to produce SVG (vectorial, scalable, editable) files, you can do the following:

dot -Tsvg > models.svg
neato -Tsvg > controllers.svg

Important: There is a bug in Graphviz tools when generating SVG 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 DOT processing you can also use Omnigraffle (on Mac OS X).

= Rake Tasks

As of Preston Lee's Rails 3/4/5 modifications, including RailRoady as a project development dependency will automatically add a set of rake tasks to your project. Sweet! (Run rake -T to check them out.)


RailRoady has been tested with the following Ruby and Rails versions


  • 1.9.2+
  • 2.0.0+


  • 3.0.3+
  • 4.0.0+
  • 5.0.0+

There are no additional requirements (nevertheless, all your Rails application requirements must be installed).

In order to view/export the DOT diagrams, you'll need the processing tools from Graphviz.

= Website and Project Home


RailRoady is distributed under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

See LICENSE for details.


Copyright (c) 2007-2008 Javier Smaldone Copyright (c) 2009 Peter Hoeg Copyright (c) 2010-2016 Preston Lee

See LICENSE for details.


Authors/Contributors (in approximate order of appearance):

  • Javier Smaldone (javier |at| smaldone |dot| com |dot| ar)
  • Elliot Smith
  • Juan Ignacio Pumarino
  • Hajime Baba
  • Ana Nelson
  • Peter Hoeg
  • John McCaffrey
  • David Jones
  • Mike Dalessio
  • Preston Lee and Lee Does, the vendor providing maintenance.
  • Tim Harvey
  • Atli Christiansen
  • John Bintz (

And of course, many thanks to the many patch submitters and testers that make this possible!