Question 1

How do I set up RuboCop Rails in an existing Rails app?

Accepted Answer

Add the gem to your Gemfile with 'require: false', then include 'plugins: rubocop-rails' in your .rubocop.yml. For autocorrection on generated code, configure config.generators.after_generate in development.rb as per the README.

Question 2

What's the difference between RuboCop and RuboCop Rails?

Accepted Answer

RuboCop is a general Ruby linter, while RuboCop Rails is an extension adding Rails-specific cops for models, controllers, etc. You need both for full Rails coverage, with RuboCop Rails complementing base RuboCop rules.

Question 3

Can RuboCop Rails fix migration violations automatically?

Accepted Answer

Yes, but with caution. Use autocorrection flags like -a or -A, but note that modifying applied migrations is discouraged; instead, create new migrations to comply with cops, as advised in the MigratedSchemaVersion documentation.

Question 4

How to ignore old migrations in RuboCop Rails?

Accepted Answer

Set MigratedSchemaVersion in your .rubocop.yml under AllCops to the timestamp of the last applied migration. This excludes older files from inspection, preventing checks on historical schema changes.

Question 5

Does RuboCop Rails work with Rails 7.2?

Accepted Answer

Yes, it supports Rails 4.2 and above. Configure TargetRailsVersion to 7.2 for version-specific checks, and leverage the built-in config.generators.apply_rubocop_autocorrect_after_generate! helper for generator integration.

Question 6

RuboCop Rails or rubocop-rails_config: which should I use?

Accepted Answer

Use rubocop-rails for versions >=2.0.0, as noted in the README. Older versions (<=1.5.0) were renamed to rubocop-rails_config, so check your gem version and update accordingly to avoid confusion.

rubocop-rails

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