prends juste note de ce que je vais te dire 

j'ai une application ruby on rails qui sert de carte en ligne pour les restaurants et permet aux restaurateurs de gérer le carte.
voici le schema de la base de données :

# This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# This file is the source Rails uses to define your schema when running `bin/rails
# db:schema:load`. When creating a new database, `bin/rails db:schema:load` tends to
# be faster and is potentially less error prone than running all of your
# migrations from scratch. Old migrations may fail to apply correctly if those
# migrations use external dependencies or application code.
#
# It's strongly recommended that you check this file into your version control system.

ActiveRecord::Schema[7.2].define(version: 2024_09_30_200933) do
  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  create_table "categories", force: :cascade do |t|
    t.string "name"
    t.text "description"
    t.decimal "discount"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string "image"
    t.uuid "uuid", default: -> { "gen_random_uuid()" }, null: false
    t.index ["uuid"], name: "index_categories_on_uuid", unique: true
  end

  create_table "menu_items", force: :cascade do |t|
    t.bigint "menu_id"
    t.bigint "product_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["menu_id"], name: "index_menu_items_on_menu_id"
    t.index ["product_id"], name: "index_menu_items_on_product_id"
  end

  create_table "menus", force: :cascade do |t|
    t.string "name"
    t.decimal "price"
    t.text "description"
    t.decimal "discount"
    t.string "image"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.uuid "uuid", default: -> { "gen_random_uuid()" }, null: false
    t.index ["uuid"], name: "index_menus_on_uuid", unique: true
  end

  create_table "product_ingredients", force: :cascade do |t|
    t.bigint "product_id"
    t.bigint "ingredient_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["ingredient_id"], name: "index_product_ingredients_on_ingredient_id"
    t.index ["product_id"], name: "index_product_ingredients_on_product_id"
  end

  create_table "products", force: :cascade do |t|
    t.string "name"
    t.decimal "price"
    t.text "description"
    t.decimal "discount"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string "image"
    t.bigint "category_id"
    t.uuid "uuid", default: -> { "gen_random_uuid()" }, null: false
    t.boolean "is_ingredient"
    t.index ["category_id"], name: "index_products_on_category_id"
    t.index ["uuid"], name: "index_products_on_uuid", unique: true
  end

  create_table "users", force: :cascade do |t|
    t.string "email", default: "", null: false
    t.string "encrypted_password", default: "", null: false
    t.string "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer "role", default: 0
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["email"], name: "index_users_on_email", unique: true
    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
  end

  add_foreign_key "products", "categories"
end

Voici le début les classes rails pour que tu aies le contexte des relations :

class Category < ApplicationRecord
    has_many :products
    mount_uploader :image, ImageUploader

    # Override the default id in the URL with the uuid
    def to_param
        uuid
    end
end

class MenuItem < ApplicationRecord
    belongs_to :menu
    belongs_to :product
end

class Menu < ApplicationRecord
    has_many :menu_items
    has_many :products, through: :menu_items

    # Override the default id in the URL with the uuid
    def to_param
        uuid
    end
end

class ProductIngredient < ApplicationRecord
    belongs_to :product
    belongs_to :ingredient, class_name: 'Product'
end

class Product < ApplicationRecord
    mount_uploader :image, ImageUploader
    belongs_to :category, optional: true
    # Validation conditionnelle pour les produits
    validates :category, presence: true, unless: :is_ingredient
    validate :price_presence_for_sellable_items

    
    # Associations pour les menus où le produit est utilisé
    has_many :menu_items
    has_many :menus, through: :menu_items

    # Associations pour les ingrédients du produit
    has_many :product_ingredients, foreign_key: 'product_id'
    has_many :ingredients, through: :product_ingredients, source: :ingredient

    # Associations pour les ingrédients où le produit est utilisé comme ingrédient
    has_many :inverse_product_ingredients, class_name: 'ProductIngredient', foreign_key: 'ingredient_id'
    has_many :used_in_products, through: :inverse_product_ingredients, source: :product

    # Scopes pour différencier les produits des ingrédients
    scope :ingredients, -> { where(is_ingredient: true) }
    scope :products, -> { where(is_ingredient: false) }
    
    # Override the default id in the URL with the uuid
    def to_param
        uuid
    end

    private
    def price_presence_for_sellable_items
        if !is_ingredient && price.nil?
          errors.add(:price, "doit être spécifié pour les produits vendables")
        end
    end
end