# RuboCop Rails

[![Gem Version](https://badge.fury.io/rb/rubocop-rails.svg)](https://badge.fury.io/rb/rubocop-rails)
[![CI](https://github.com/rubocop/rubocop-rails/actions/workflows/test.yml/badge.svg)](https://github.com/rubocop/rubocop-rails/actions/workflows/test.yml)

A [RuboCop](https://github.com/rubocop/rubocop) extension focused on enforcing Rails best practices and coding conventions.

> [!IMPORTANT]
> This repository manages rubocop-rails gem (>= 2.0.0). rubocop-rails gem (<= 1.5.0) has been renamed to [rubocop-rails_config](https://rubygems.org/gems/rubocop-rails_config) gem.

## Installation

Just install the `rubocop-rails` gem

```sh
$ gem install rubocop-rails
```

or if you use bundler put this in your `Gemfile`

```ruby
gem 'rubocop-rails', require: false
```

## Usage

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`.

```yaml
plugins: rubocop-rails
```

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

```yaml
plugins:
  - rubocop-other-extension
  - rubocop-rails
```

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

> [!NOTE]
> The plugin system is supported in RuboCop 1.72+. In earlier versions, use `require` instead of `plugins`.

### Command line

```sh
$ rubocop --plugin rubocop-rails
```

### Rake task

```ruby
require 'rubocop/rake_task'

RuboCop::RakeTask.new do |task|
  task.plugins << 'rubocop-rails'
end
```

## RuboCop Rails configuration

The following settings specific to RuboCop Rails can be configured in `.rubocop.yml`.

### `AllCops: TargetRailsVersion`

What version of Rails is the inspected code using? If a value is specified
for `TargetRailsVersion` then it is used. Acceptable values are specified
as a float (e.g., 7.2); the patch version of Rails should not be included.

```yaml
AllCops:
  TargetRailsVersion: 7.2
```

If `TargetRailsVersion` is not set, RuboCop will parse the Gemfile.lock or
gems.locked file to find the version of Rails that has been bound to the
application. If neither of those files exist, RuboCop will use Rails 5.0
as the default.

### `AllCops: MigratedSchemaVersion`

By specifying the `MigratedSchemaVersion` option, migration files that have already been run can be ignored.
When `MigratedSchemaVersion: '20241225000000'` is set, migration files lower than or equal to '20241225000000' will be ignored.
For example, to ignore db/migrate/20241225000000_create_articles.rb and earlier migrations you would configure it the following way:

```yaml
AllCops:
  MigratedSchemaVersion: '20241225000000'
```

This prevents inspecting schema settings for already applied migration files.
Changing already applied migrations should be avoided because it can lead to the schema getting out of sync
between your local copy and what it actually is in production, depending on when `bin/rails db:migrate` was executed.
If you want to modify your schema to comply with the cops, you should instead create new migrations.

## Rails configuration tip

In Rails 6.1+, 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`.

```ruby
# 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)
    end
  end
end
```

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.

In Rails 7.2+, it is recommended to use `config.generators.apply_rubocop_autocorrect_after_generate!` instead of the above setting:

```diff
 # config/environments/development.rb
 Rails.application.configure do
   (snip)
   # Apply autocorrection by RuboCop to files generated by `bin/rails generate`.
-  # config.generators.apply_rubocop_autocorrect_after_generate!
+  config.generators.apply_rubocop_autocorrect_after_generate!
 end
```

You only need to uncomment.

## The Cops

All cops are located under
[`lib/rubocop/cop/rails`](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:

```yaml
Rails/FindBy:
  Exclude:
    - lib/example.rb
```

## Documentation

You can read a lot more about RuboCop Rails in its [official docs](https://docs.rubocop.org/rubocop-rails/).

## Compatibility

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](https://img.shields.io/badge/code_style-rubocop-brightgreen.svg)](https://github.com/rubocop/rubocop-rails)

[![Rails Style Guide](https://img.shields.io/badge/code_style-community-brightgreen.svg)](https://rails.rubystyle.guide)

Here are the Markdown snippets for the two badges:

``` markdown
[![Rails Style Guide](https://img.shields.io/badge/code_style-rubocop-brightgreen.svg)](https://github.com/rubocop/rubocop-rails)

[![Rails Style Guide](https://img.shields.io/badge/code_style-community-brightgreen.svg)](https://rails.rubystyle.guide)
```

## Contributing

Checkout the [contribution guidelines](CONTRIBUTING.md).

## License

`rubocop-rails` is MIT licensed. [See the accompanying file](LICENSE.txt) for
the full text.
