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
4. Implement — Write controllers, models, add Hotwire (see Reference Guide below)
5. 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
6. 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+1posts = Post.allposts.each { |post| puts post.author.name }
# GOOD — eager load associationposts = Post.includes(:author).allposts.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.rbdef index  @posts = Post.includes(:author).page(params[:page])  @next_page = @posts.next_pageend

Sidekiq Worker Template

# app/jobs/send_welcome_email_job.rbclass 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  endend
# Enqueue from controller or model callbackSendWelcomeEmailJob.perform_later(user.id)

Strong Parameters (controller template)

# app/controllers/posts_controller.rbclass 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)  endend

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:

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

Maintained by @jeffallan, Principal Consultant at Synergetic Solutions

Documentation