# Rails Dev

> Community Ruby on Rails Development Best Practices

- Skill: `comeonoliver/rails-dev` (Agent Skill)
- Install (CLI): `npx skillmds@latest add comeonoliver/rails-dev`
- Raw SKILL.md: https://api.skillmd.com/api/skills/comeonoliver/rails-dev/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ComeOnOliver (https://skillmd.com/u/comeonoliver)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/comeonoliver/rails-dev

---

# Community Ruby on Rails Development Best Practices

Comprehensive performance and maintainability optimization guide for Ruby on Rails applications, maintained by Community. Contains 45 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.

## When to Apply

Reference these guidelines when:
- Writing new Rails controllers, models, or views
- Optimizing ActiveRecord queries and database access patterns
- Implementing caching strategies (fragment, Russian doll, low-level)
- Building or refactoring API endpoints
- Adding Turbo Frames and Streams for interactive UIs
- Reviewing code for N+1 queries and security vulnerabilities
- Designing background jobs with Sidekiq or Active Job
- Writing or reviewing database migrations

## Rule Categories by Priority

| Priority | Category | Impact | Prefix |
|----------|----------|--------|--------|
| 1 | Database & ActiveRecord | CRITICAL | `db-` |
| 2 | Controllers & Routing | CRITICAL | `ctrl-` |
| 3 | Security | HIGH | `sec-` |
| 4 | Models & Business Logic | HIGH | `model-` |
| 5 | Caching & Performance | HIGH | `cache-` |
| 6 | Views & Frontend | MEDIUM-HIGH | `view-` |
| 7 | API Design | MEDIUM | `api-` |
| 8 | Background Jobs & Async | LOW-MEDIUM | `job-` |

## Quick Reference

### 1. Database & ActiveRecord (CRITICAL)

- [`db-eager-load-associations`](references/db-eager-load-associations.md) - Eager load associations to eliminate N+1 queries
- [`db-add-database-indexes`](references/db-add-database-indexes.md) - Add database indexes on queried columns
- [`db-select-specific-columns`](references/db-select-specific-columns.md) - Select only needed columns
- [`db-batch-processing`](references/db-batch-processing.md) - Use find_each for large dataset iteration
- [`db-avoid-queries-in-loops`](references/db-avoid-queries-in-loops.md) - Avoid database queries inside loops
- [`db-use-scopes`](references/db-use-scopes.md) - Define reusable query scopes on models
- [`db-safe-migrations`](references/db-safe-migrations.md) - Write reversible zero-downtime migrations
- [`db-exists-over-count`](references/db-exists-over-count.md) - Use exists? instead of count for existence checks

### 2. Controllers & Routing (CRITICAL)

- [`ctrl-thin-controllers`](references/ctrl-thin-controllers.md) - Keep controllers thin by delegating to models and services
- [`ctrl-strong-params`](references/ctrl-strong-params.md) - Always use strong parameters for mass assignment
- [`ctrl-restful-routes`](references/ctrl-restful-routes.md) - Follow RESTful routing conventions
- [`ctrl-before-action-scoping`](references/ctrl-before-action-scoping.md) - Scope before_action callbacks with only/except
- [`ctrl-respond-to-format`](references/ctrl-respond-to-format.md) - Use respond_to for multi-format responses
- [`ctrl-rescue-from`](references/ctrl-rescue-from.md) - Handle errors with rescue_from in controllers

### 3. Security (HIGH)

- [`sec-parameterized-queries`](references/sec-parameterized-queries.md) - Never interpolate user input in SQL
- [`sec-strong-params-whitelist`](references/sec-strong-params-whitelist.md) - Whitelist permitted params, never blacklist
- [`sec-authenticate-before-authorize`](references/sec-authenticate-before-authorize.md) - Authenticate before authorize on every request
- [`sec-csrf-protection`](references/sec-csrf-protection.md) - Enable CSRF protection for all form submissions
- [`sec-scope-queries-to-user`](references/sec-scope-queries-to-user.md) - Scope queries to current user for authorization

### 4. Models & Business Logic (HIGH)

- [`model-validate-at-model-level`](references/model-validate-at-model-level.md) - Validate data at the model level
- [`model-avoid-callback-side-effects`](references/model-avoid-callback-side-effects.md) - Avoid side effects in model callbacks
- [`model-use-service-objects`](references/model-use-service-objects.md) - Extract complex logic into service objects
- [`model-scope-over-class-methods`](references/model-scope-over-class-methods.md) - Use scopes instead of class methods for query composition
- [`model-use-enums`](references/model-use-enums.md) - Use enums for finite state fields
- [`model-concerns-for-shared-behavior`](references/model-concerns-for-shared-behavior.md) - Use concerns for shared model behavior
- [`model-query-objects`](references/model-query-objects.md) - Extract complex queries into query objects

### 5. Caching & Performance (HIGH)

- [`cache-fragment-caching`](references/cache-fragment-caching.md) - Use fragment caching for expensive view partials
- [`cache-russian-doll`](references/cache-russian-doll.md) - Use Russian doll caching for nested collections
- [`cache-low-level`](references/cache-low-level.md) - Use Rails.cache.fetch for computed data
- [`cache-counter-cache`](references/cache-counter-cache.md) - Use counter caches for association counts
- [`cache-conditional-get`](references/cache-conditional-get.md) - Use conditional GET with stale? for HTTP caching

### 6. Views & Frontend (MEDIUM-HIGH)

- [`view-collection-rendering`](references/view-collection-rendering.md) - Use collection rendering instead of loop partials
- [`view-turbo-frames`](references/view-turbo-frames.md) - Use Turbo Frames for partial page updates
- [`view-turbo-streams`](references/view-turbo-streams.md) - Use Turbo Streams for real-time page mutations
- [`view-form-with`](references/view-form-with.md) - Use form_with instead of form_tag or form_for
- [`view-avoid-logic-in-views`](references/view-avoid-logic-in-views.md) - Move display logic to helpers or presenters

### 7. API Design (MEDIUM)

- [`api-serializers`](references/api-serializers.md) - Use serializers for consistent JSON responses
- [`api-pagination`](references/api-pagination.md) - Always paginate collection endpoints
- [`api-versioning`](references/api-versioning.md) - Version APIs from day one
- [`api-error-responses`](references/api-error-responses.md) - Return structured error responses
- [`api-avoid-jbuilder-hot-paths`](references/api-avoid-jbuilder-hot-paths.md) - Avoid Jbuilder on high-traffic endpoints

### 8. Background Jobs & Async (LOW-MEDIUM)

- [`job-idempotent-design`](references/job-idempotent-design.md) - Design jobs to be idempotent
- [`job-small-payloads`](references/job-small-payloads.md) - Pass IDs to jobs, not serialized objects
- [`job-error-handling`](references/job-error-handling.md) - Configure retry and error handling for jobs
- [`job-unique-jobs`](references/job-unique-jobs.md) - Prevent duplicate job enqueuing

## How to Use

Read individual reference files for detailed explanations and code examples:

- [Section definitions](references/_sections.md) - Category structure and impact levels
- [Rule template](assets/templates/_template.md) - Template for adding new rules

## Reference Files

| File | Description |
|------|-------------|
| [references/_sections.md](references/_sections.md) | Category definitions and ordering |
| [assets/templates/_template.md](assets/templates/_template.md) | Template for new rules |
| [metadata.json](metadata.json) | Version and reference information |