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Generate Mermaid ERD from your Ruby on Rails application.

Demo Page

Mermaid ERD can be generated at will. The generated ERD can be copied in Markdown format, so they can be easily shared on GitHub. You can also save it as an image, so it can be used in environments where Mermaid is not available. The editor is a single HTML file, so the entire editor can be shared.

Add this line to your application's Gemfile:

gem "rails-mermaid_erd", group: :development, require: false

And then execute:

$ bundle install

Add this line to your application's Rakefile:

begin
  require "rails-mermaid_erd"
rescue LoadError
  # Do nothing.
end

Run rake task mermaid_erd will generate <app_root>/mermaid_erd/index.html.

$ bundle exec rails mermaid_erd
# or
$ bundle exec rake mermaid_erd

Simply open the generated <app_root>/mermaid_erd/index.html in your browser.

This file is not required for Git management, so you can add it to .gitignore if necessary

mermaid_erd

<app_root>/mermaid_erd/index.html is a single HTML file. If you share this file, it can be used by those who do not have a Ruby on Rails environment. Or, you can upload the file to a web server and share it with the same URL.

It would be very smart to generate it automatically using CI.

./config/mermaid_erd.yml to customize the configuration. See ./docs/example.yml for an example configuration.

The setting items are as follows.

The gem is available as open source under the terms of the MIT License.