Vanilla Rails Models

Rich domain models with concerns. Decompose with concerns, not services.

For method ordering and private indentation rules, see vanilla-rails-style.

State as Separate Records (NOT Booleans)

Don't use boolean columns for state. Create state records that capture who/when.

# Bad - boolean
add_column :cards, :starred, :boolean, default: false

# Good - state record
create_table :stars, id: :uuid do |t|
  t.uuid :card_id, null: false
  t.uuid :user_id, null: false
  t.timestamps
end

class Card < ApplicationRecord
  has_one :star, dependent: :destroy

  def star(user: Current.user)
    create_star!(user: user) unless starred?
  end

  def starred?
    star.present?
  end
end

Binary state (one per item): has_one — closure, triage, goldness

Multi-user state: has_many — pins, watches, assignments

Concerns as Adjectives, Namespaced Under Model

Name as adjectives (-able/-ible ONLY). Namespace under the model. File at app/models/card/closeable.rb.

Wrong	Right	Why
Card::Closing	Card::Closeable	Verb → adjective
Card::Stars	Card::Starrable	Noun → adjective
Card::Closed	Card::Closeable	Past participle → capability
Starrable	Card::Starrable	Must namespace under model
concerns/starrable.rb	card/starrable.rb	File under model directory

Full pattern:

# app/models/card/closeable.rb
module Card::Closeable
  extend ActiveSupport::Concern

  included do
    has_one :closure, dependent: :destroy
    scope :closed, -> { joins(:closure) }
    scope :open, -> { where.missing(:closure) }
  end

  def close(user: Current.user)
    unless closed?
      transaction do
        create_closure!(user: user)
        track_event :closed, creator: user
      end
    end
  end

  def reopen(user: Current.user)
    if closed?
      transaction do
        closure&.destroy
        track_event :reopened, creator: user
      end
    end
  end

  def closed?
    closure.present?
  end
end

Multi-user pattern:

module Card::Pinnable
  extend ActiveSupport::Concern

  included do
    has_many :pins, dependent: :destroy
  end

  def pinned_by?(user)
    pins.exists?(user: user)
  end

  def pin_by(user)
    pins.find_or_create_by!(user: user)
  end

  def unpin_by(user)
    pins.find_by(user: user)&.destroy
  end
end

When to Extract

• Feature adds 3+ methods to model
• Clear adjective name exists (-able/-ible)
• Even if only one model uses it (decomposition, not just reuse)
• Model exceeds ~100 lines

Red Flags

Red flag	Fix
Boolean column for state	State record table (see data-modeling)
Concern not ending in -able/-ible	Rename immediately
Concern not namespaced under model	Move to Card::Closeable
Concern in app/models/concerns/ for single model	Move to app/models/card/
Service object for domain logic	Rich model method instead
"Only extract if reused"	Extract for decomposition at 3+ methods