Favoritable concern

create_favorite_records.rb

class CreateFavoriteRecords < ActiveRecord::Migration[7.2]
  def change
    create_table :favorite_records, id: :uuid do |t|
      t.references :owner, foreign_key: { to_table: :users }, null: false, type: :uuid
      t.references :favoritable, polymorphic: true, null: false, type: :uuid

      t.timestamps
    end

    add_index :favorite_records, [:owner_id, :favoritable_type, :favoritable_id], unique: true, name: 'index_favorite_records_uniqueness'
  end
end

favoritable.rb

module Favoritable
  extend ActiveSupport::Concern

  included do
    has_many :favorite_records, class_name: 'FavoriteRecord', as: :favoritable, dependent: :destroy, inverse_of: :favoritable

    scope :favorite, -> { favorited_by(Current.user) }
    scope :favorited_by, ->(owner) { joins(:favorite_records).where(favorite_records: { owner: }) }
    scope :not_favorite, -> { where.missing(:favorite_records) }
  end

  def favorite! = favorite_records.create!(owner: Current.user)
  def unfavorite! = favorite_record_for(Current.user)&.destroy
  def favorited_by?(user) = favorite_record_for(user).present?
  def favorite? = favorited_by?(Current.user)
  def favoritable_sgid = to_sgid(for: :favoritable, expires_in: nil)

  private

  def favorite_record_for(user) = favorite_records.find { _1.owner_id == user.id }
end

favorite_record.rb

class FavoriteRecord < ApplicationRecord
  belongs_to :owner, class_name: 'User'
  belongs_to :favoritable, polymorphic: true

  validates :owner, uniqueness: { scope: [:favoritable_type, :favoritable_id] }
end

favorite_records_controller.rb

class FavoriteRecordsController < ApplicationController
  before_action :set_favoritable

  def create
    @favoritable.favorite!

    redirect_back_or_to @favoritable
  end

  def destroy
    @favoritable.unfavorite!

    redirect_back_or_to @favoritable
  end

  private

  def set_favoritable
    @favoritable = GlobalID::Locator.locate_signed(params[:favoritable_sgid], for: :favoritable)
  end
end

note.rb

class Note < ApplicationRecord
  include Favoritable
end

routes.rb

Rails.application.routes.draw do
  resource :favorite_records, param: :favoritable_sgid, only: %i[create destroy]
end