dhh-rails-style

<essential_principles>

Core Philosophy

"The best code is the code you don't write. The second best is the code that's obviously correct."

Vanilla Rails is plenty:

• •Rich domain models over service objects
• •CRUD controllers over custom actions
• •Concerns for horizontal code sharing
• •Records as state instead of boolean columns
• •Database-backed everything (no Redis)
• •Build solutions before reaching for gems

What they deliberately avoid:

• •devise (custom ~150-line auth instead)
• •pundit/cancancan (simple role checks in models)
• •sidekiq (Solid Queue uses database)
• •redis (database for everything)
• •view_component (partials work fine)
• •GraphQL (REST with Turbo sufficient)
• •factory_bot (fixtures are simpler)
• •rspec (Minitest ships with Rails)
• •Tailwind (native CSS with layers)

Development Philosophy:

• •Ship, Validate, Refine - prototype-quality code to production to learn
• •Fix root causes, not symptoms
• •Write-time operations over read-time computations
• •Database constraints over ActiveRecord validations </essential_principles>

1. •Controllers - REST mapping, concerns, Turbo responses, API patterns
2. •Models - Concerns, state records, callbacks, scopes, POROs
3. •Views & Frontend - Turbo, Stimulus, CSS, partials
4. •Architecture - Routing, multi-tenancy, authentication, jobs, caching
5. •Testing - Minitest, fixtures, integration tests
6. •Gems & Dependencies - What to use vs avoid
7. •Code Review - Review code against DHH style
8. •General Guidance - Philosophy and conventions

Specify a number or describe your task. </intake>

After reading relevant references, apply patterns to the user's code. </routing>

<quick_reference>

Naming Conventions

Verbs: card.close, card.gild, board.publish (not set_style methods)

Predicates: card.closed?, card.golden? (derived from presence of related record)

Concerns: Adjectives describing capability (Closeable, Publishable, Watchable)

Controllers: Nouns matching resources (Cards::ClosuresController)

Scopes:

• •chronologically, reverse_chronologically, alphabetically, latest
• •preloaded (standard eager loading name)
• •indexed_by, sorted_by (parameterized)
• •active, unassigned (business terms, not SQL-ish)

REST Mapping

Instead of custom actions, create new resources:

POST /cards/:id/close    → POST /cards/:id/closure
DELETE /cards/:id/close  → DELETE /cards/:id/closure
POST /cards/:id/archive  → POST /cards/:id/archival

Ruby Syntax Preferences

# Symbol arrays with spaces inside brackets
before_action :set_message, only: %i[ show edit update destroy ]

# Private method indentation
  private
    def set_message
      @message = Message.find(params[:id])
    end

# Expression-less case for conditionals
case
when params[:before].present?
  messages.page_before(params[:before])
else
  messages.last_page
end

# Bang methods for fail-fast
@message = Message.create!(params)

# Ternaries for simple conditionals
@room.direct? ? @room.users : @message.mentionees

Key Patterns

State as Records:

Card.joins(:closure)         # closed cards
Card.where.missing(:closure) # open cards

Current Attributes:

belongs_to :creator, default: -> { Current.user }

Authorization on Models:

class User < ApplicationRecord
  def can_administer?(message)
    message.creator == self || admin?
  end
end

</quick_reference>

<reference_index>

Domain Knowledge

All detailed patterns in references/:

<success_criteria> Code follows DHH style when:

• •Controllers map to CRUD verbs on resources
• •Models use concerns for horizontal behavior
• •State is tracked via records, not booleans
• •No unnecessary service objects or abstractions
• •Database-backed solutions preferred over external services
• •Tests use Minitest with fixtures
• •Turbo/Stimulus for interactivity (no heavy JS frameworks)
• •Native CSS with modern features (layers, OKLCH, nesting)
• •Authorization logic lives on User model
• •Jobs are shallow wrappers calling model methods </success_criteria>

Important Disclaimers:

• •LLM-generated guide - may contain inaccuracies
• •Code examples from Fizzy are licensed under the O'Saasy License
• •Not affiliated with or endorsed by 37signals