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Generate Entity-Relationship Diagrams for Rails applications
Tag: v0.1.0

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Rails ERD - Generate Entity-Relationship Diagrams for Rails applications

Rails ERD is a Rails plugin that allows you to easily generate diagrams based on your ActiveRecord models. The diagrams give a great overview of how your models are related. Having a diagram that describes your models is perfect documentation for your application.

Rails ERD was created specifically for Rails 3. It uses ActiveRecord reflection to figure out how your models are associated.

Getting started

In its most simple form, Rails ERD is a plugin for Rails 3 that provides you with a Rake task to create an Entity-Relationship Diagram. It depends on the Graphviz visualisation library. You have to install Graphviz before using Rails ERD. In order to create PDF files (the default), you should install or compile Graphviz with Pango/Cairo.

For example, to install Graphviz with MacPorts:

% sudo port install graphviz

Or with Homebrew:

% brew install cairo pango graphviz

Next, install Rails ERD. Open your Gemfile, and add the following:

group :development do
  gem 'rails-erd'

Tell Bundler to install Rails ERD:

% bundle install

You now have access to Rails ERD through Rake. Generate a new Entity-Relationship Diagram for your Rails application:

% rake erd

All done! You will now have a file named ERD.pdf in your application root.

Advanced use

Rails ERD has several options that you can use to customise its behaviour. All options can be provided on the command line. For example:

% rake erd exclude_timestamps=false

For an overview of all available options, see the documentation of RailsERD:


Rails ERD is released under the MIT license.

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