RuboCop Rails

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A RuboCop extension focused on enforcing Rails best practices and coding conventions.

Note: This repository manages rubocop-rails gem (>= 2.0.0). rubocop-rails gem (<= 1.5.0) has been renamed to rubocop-rails_config gem.


Just install the rubocop-rails gem

$ gem install rubocop-rails

or if you use bundler put this in your Gemfile

gem 'rubocop-rails', require: false


You need to tell RuboCop to load the Rails extension. There are three ways to do this:

RuboCop configuration file

Put this into your .rubocop.yml.

require: rubocop-rails

Alternatively, use the following array notation when specifying multiple extensions.

  - rubocop-other-extension
  - rubocop-rails

Now you can run rubocop and it will automatically load the RuboCop Rails cops together with the standard cops.

Command line

$ rubocop --require rubocop-rails

Note: --rails option is required while rubocop command supports --rails option.

Rake task

require 'rubocop/rake_task' do |task|
  task.requires << 'rubocop-rails'

Rails configuration tip

If you are using Rails 6.1 or newer, add the following config.generators.after_generate setting to your config/environments/development.rb to apply RuboCop autocorrection to code generated by bin/rails g.

# config/environments/development.rb
Rails.application.configure do
  config.generators.after_generate do |files|
    parsable_files = files.filter { |file| file.end_with?('.rb') }
    unless parsable_files.empty?
      system("bundle exec rubocop -A --fail-level=E #{parsable_files.shelljoin}", exception: true)

It uses rubocop -A to apply Style/FrozenStringLiteralComment and other unsafe autocorrection cops. rubocop -A is unsafe autocorrection, but code generated by default is simple and less likely to be incompatible with rubocop -A. If you have problems you can replace it with rubocop -a instead.

The Cops

All cops are located under lib/rubocop/cop/rails, and contain examples/documentation.

In your .rubocop.yml, you may treat the Rails cops just like any other cop. For example:

    - lib/example.rb


You can read a lot more about RuboCop Rails in its official docs.


Rails cops support the following versions:

  • Rails 4.2+

Readme Badge

If you use RuboCop Rails in your project, you can include one of these badges in your readme to let people know that your code is written following the community Rails Style Guide.

Rails Style Guide

Rails Style Guide

Here are the Markdown snippets for the two badges:

[![Rails Style Guide](](

[![Rails Style Guide](](


Checkout the contribution guidelines.


rubocop-rails is MIT licensed. See the accompanying file for the full text.