Rails Expert

Rails Expert

Core Workflow

1. Analyze requirements — Identify models, routes, real-time needs, background jobs
2. Scaffold resources — rails generate model User name:string email:string, rails generate controller Users
3. Run migrations — rails db:migrate and verify schema with rails db:schema:dump

• If migration fails: inspect db/schema.rb for conflicts, rollback with rails db:rollback, fix and retry

1. Implement — Write controllers, models, add Hotwire (see Reference Guide below)
2. Validate — bundle exec rspec must pass; bundle exec rubocop for style

• If specs fail: check error output, fix failing examples, re-run with --format documentation for detail
• If N+1 queries surface during review: add includes/eager_load (see Common Patterns) and re-run specs

1. Optimize — Audit for N+1 queries, add missing indexes, add caching

Reference Guide

Load detailed guidance based on context:

| Topic | Reference | Load When | |-------|-----------|-----------| | Hotwire/Turbo | references/hotwire-turbo.md | Turbo Frames, Streams, Stimulus controllers | | Active Record | references/active-record.md | Models, associations, queries, performance | | Background Jobs | references/background-jobs.md | Sidekiq, job design, queues, error handling | | Testing | references/rspec-testing.md | Model/request/system specs, factories | | API Development | references/api-development.md | API-only mode, serialization, authentication |

Common Patterns

N+1 Prevention with includes/eager_load

# BAD — triggers N+1
posts = Post.all
posts.each { |post| puts post.author.name }

# GOOD — eager load association
posts = Post.includes(:author).all
posts.each { |post| puts post.author.name }

# GOOD — eager_load forces a JOIN (useful when filtering on association)
posts = Post.eager_load(:author).where(authors: { verified: true })

Turbo Frame Setup (partial page update)

# app/controllers/posts_controller.rb
def index
  @posts = Post.includes(:author).page(params[:page])
  @next_page = @posts.next_page
end

Sidekiq Worker Template

# app/jobs/send_welcome_email_job.rb
class SendWelcomeEmailJob  e
    Rails.logger.warn("SendWelcomeEmailJob: user #{user_id} not found — #{e.message}")
    # Do not re-raise; record is gone, no point retrying
  end
end

# Enqueue from controller or model callback
SendWelcomeEmailJob.perform_later(user.id)

Strong Parameters (controller template)

# app/controllers/posts_controller.rb
class PostsController 95% coverage
- Use service objects for complex business logic; keep controllers thin
- Add database indexes for every column used in `WHERE`, `ORDER BY`, or `JOIN`
- Offload slow operations to Sidekiq — never run them synchronously in a request cycle

### MUST NOT DO
- Skip migrations for schema changes
- Use raw SQL without sanitization (`sanitize_sql` or parameterized queries only)
- Expose internal IDs in URLs without consideration

## Output Templates

When implementing Rails features, provide:
1. Migration file (if schema changes needed)
2. Model file with associations and validations
3. Controller with RESTful actions and strong parameters
4. View files or Hotwire setup
5. Spec files for models and requests
6. Brief explanation of architectural decisions

[Documentation](https://jeffallan.github.io/claude-skills/skills/backend/rails-expert/)

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [Jeffallan](https://github.com/Jeffallan)
- **Source:** [Jeffallan/claude-skills](https://github.com/Jeffallan/claude-skills)
- **License:** MIT

Install and usage instructions live in the source repository linked above.