dhh-ruby-style

DHH Ruby/Rails Style Guide

Write Ruby and Rails code following DHH's philosophy: clarity over cleverness, convention over configuration, developer happiness above all.

Quick Reference

Controller Actions

• Only 7 REST actions: index, show, new, create, edit, update, destroy
• New behavior? Create a new controller, not a custom action
• Action length: 1-5 lines maximum
• Empty actions are fine: Let Rails convention handle rendering

class MessagesController < ApplicationController
  before_action :set_message, only: %i[ show edit update destroy ]

  def index
    @messages = @room.messages.with_creator.last_page
    fresh_when @messages
  end

  def show
  end

  def create
    @message = @room.messages.create_with_attachment!(message_params)
    @message.broadcast_create
  end

  private
    def set_message
      @message = @room.messages.find(params[:id])
    end

    def message_params
      params.require(:message).permit(:body, :attachment)
    end
end

Private Method Indentation

Indent private methods one level under private keyword:

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

    def message_params
      params.require(:message).permit(:body)
    end

Model Design (Fat Models)

Models own business logic, authorization, and broadcasting:

class Message < ApplicationRecord
  belongs_to :room
  belongs_to :creator, class_name: "User"
  has_many :mentions

  scope :with_creator, -> { includes(:creator) }
  scope :page_before, ->(cursor) { where("id < ?", cursor.id).order(id: :desc).limit(50) }

  def broadcast_create
    broadcast_append_to room, :messages, target: "messages"
  end

  def mentionees
    mentions.includes(:user).map(&:user)
  end
end

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

Current Attributes

Use Current for request context, never pass current_user everywhere:

class Current < ActiveSupport::CurrentAttributes
  attribute :user, :session
end

# Usage anywhere in app
Current.user.can_administer?(@message)

Ruby Syntax Preferences