rails-expert skill

by Jeffallan·Jeffallan/claude-skills·12k stars·MIT

Rails 7+ specialist that optimizes Active Record queries with includes/eager_load, implements Turbo Frames and Turbo Streams for partial page updates, configures Action Cable for WebSocket connections, sets up Sidekiq workers for background job processing, and writes comprehensive RSpec test suites. Use when building Rails 7+ web applications with Hotwire, real-time features, or background job processing. Invoke for Active Record optimization, Turbo Frames/Streams, Action Cable, Sidekiq, RSpec Rails.

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Install the rails-expert skill

A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description.

git clone --depth 1 https://github.com/Jeffallan/claude-skills.git /tmp/claude-skills
mkdir -p ~/.claude/skills
cp -r /tmp/claude-skills/skills/rails-expert ~/.claude/skills/rails-expert

available in every project

In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub

The instructions your agent would load

SKILL.md as published, without the frontmatter. Read it on GitHub

Rails Expert

Core Workflow

Analyze requirements — Identify models, routes, real-time needs, background jobs
Scaffold resources — rails generate model User name:string email:string, rails generate controller Users
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

Implement — Write controllers, models, add Hotwire (see Reference Guide below)
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

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

Reference Guide

Load detailed guidance based on context:

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/views/posts/index.html.erb %>
<%= turbo_frame_tag "posts" do %>
  <%= render @posts %>
  <%= link_to "Load More", posts_path(page: @next_page) %>
<% end %>

<%# app/views/posts/_post.html.erb %>
<%= turbo_frame_tag dom_id(post) do %>
  <h2><%= post.title %></h2>
  <%= link_to "Edit", edit_post_path(post) %>
<% end %>

# 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 < ApplicationJob
  queue_as :default
  sidekiq_options retry: 3, dead: false

  def perform(user_id)
    user = User.find(user_id)
    UserMailer.welcome(user).deliver_now
  rescue ActiveRecord::RecordNotFound => 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 < ApplicationController
  before_action :set_post, only: %i[show edit update destroy]

  def create
    @post = Post.new(post_params)
    if @post.save
      redirect_to @post, notice: "Post created."
    else
      render :new, status: :unprocessable_entity
    end
  end

  private

  def set_post
    @post = Post.find(params[:id])
  end

  def post_params
    params.require(:post).permit(:title, :body, :published_at)
  end
end

Constraints

MUST DO

Prevent N+1 queries with includes/eager_load on every collection query involving associations
Write comprehensive specs targeting >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:

Migration file (if schema changes needed)
Model file with associations and validations
Controller with RESTful actions and strong parameters
View files or Hotwire setup
Spec files for models and requests
Brief explanation of architectural decisions

Documentation

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