Conventions and best practices for building web applications with Ruby on Rails. Use when scaffolding Rails apps or generators, designing ActiveRecord models and migrations, wiring up Hotwire/Turbo/Stimulus interactivity, setting up background jobs or caching, or writing RSpec/Minitest coverage for

Ruby on Rails This skill covers Ruby and Ruby on Rails development, including Rails conventions, ActiveRecord patterns, frontend integration, security, and testing. Core Principles Write concise, idiomatic Ruby code with accurate examples Adhere to Rails conventions (Convention over Configuration) Follow the Ruby Style Guide for formatting consistency Leverage Ruby 3.x features like pattern matching and endless methods Prefer Rails command line generators ( bin/rails generate ... ) over hand written boilerplate — they keep files consistent with framework conventions and wire up tests/routes automatically Use bin/dev to run the local development server (it boots the web process plus any configured watchers) and check logs after significant changes Naming Conventions Use snake case for files, methods, and variables Use CamelCase for classes and modules Follow Rails naming conventions for models, controllers, views Architecture & Performance Utilize ActiveRecord for database operations with proper indexing Use PostgreSQL in production, with proper indexes, connection pooling, and safe/reversible migrations Implement eager loading to prevent N+1 query problems Apply fragment caching and Russian Doll caching strategies Use service objects for complex business logic Follow MVC architecture strictly Keep controllers RESTful and focused Rails 8 Defaults Rails 8 ships with a "no PaaS needed" stack — favor these built ins over adding external services unless there's a specific reason not to: Solid Queue — database backed ActiveJob adapter; use it as the default background job backend instead of standing up Redis/Sidekiq unless job volume or feature needs (e.g., Sidekiq Pro batches) require it Solid Cache — database backed cache store; a reasonable default for Rails.cache without a separate Redis/Memcached deployment Solid Cable — database backed Action Cable adapter for WebSockets without Redis Propshaft — the default asset pipeline; simpler than Sprockets, just serves fingerprinted files without a bundling step Kamal — the default deployment tool for shipping containerized Rails apps to your own servers Frontend & UI Employ Hotwire (Turbo and Stimulus) for standard Rails interactivity and dynamic interactions without full page reloads Reach for a Vite managed JS pipeline (e.g., vite rails) only when you actually need npm managed JavaScript (React/Vue components, complex bundling) — don't add it by default Design responsively with Tailwind CSS Maintain DRY views through helpers and partials Use ViewComponents for reusable UI components Security Implement authentication/authorization via Devise or Pundit Use strong parameters in controllers to prevent mass assignment vulnerabilities Sanitize user inputs appropriately Use CSRF protection tokens Implement proper session management Testing Write comprehensive Minitest or RSpec coverage for models, controllers, and integration flows, following TDD practices Use FactoryBot for test data generation rather than fixtures Mock external services; stub predefined return values Use shared examples for common behaviors across different contexts Ensure each test is independent; avoid shared state between tests Best Practices Keep controllers thin, models fat (but not too fat) Use concerns for shared functionality Implement background jobs with Sidekiq or ActiveJob Use proper database migrations Follow RESTful routing conventions

ruby-rails