Ruby on Railsda modellarning merosxo'rligi yoki…

Ruby on Rails'da modellarning merosxo'rligi Single Table Inheritance (STI) yoki polimorfik aloqalar orqali amalga oshiriladi.

Single Table Inheritance (STI)

STI turli ob'ekt turlari o'xshash atributlarga ega, ammo turli xulq-atvorlarga ega bo'lsa, mos keladi. Barcha ma'lumotlar bitta jadvalda saqlanadi va ob'ekt turi type ustuni orqali aniqlanadi.

Jadval va type ustunini yaratish:

# migration
create_table :animals do |t|
  t.string :name
  t.string :type
  t.timestamps
end

Asosiy klassdan meros olgan modellarning yaratilishi:

# app/models/animal.rb
class Animal < ApplicationRecord
  # Umumiy logika
end

# app/models/dog.rb
class Dog < Animal
  # Itlar uchun maxsus logika
  def bark
    "Woof!"
  end
end

# app/models/cat.rb
class Cat < Animal
  # Mushuklar uchun maxsus logika
  def meow
    "Meow!"
  end
end

Foydalanish:

# konsol
dog = Dog.create(name: "Buddy")
cat = Cat.create(name: "Whiskers")

animal = Animal.find(dog.id) # Dog ob'ekti qaytaradi

Polimorfik aloqalar

Polimorfik aloqalar, model turli xil boshqa modellarga tegishli bo'lishi mumkin bo'lsa, ishlatiladi.

Aloqador modelda _id va _type ustunlarini qo'shish: Masalan, Comment Article yoki Photo ga tegishli bo'lishi mumkin:

# migration
create_table :comments do |t|
  t.text :body
  t.references :commentable, polymorphic: true, null: false
  t.timestamps
end

Modellarda aloqani e'lon qilish: Comment modelida:

# app/models/comment.rb
class Comment < ApplicationRecord
  belongs_to :commentable, polymorphic: true
end

Article va Photo modellarda:

# app/models/article.rb
class Article < ApplicationRecord
  has_many :comments, as: :commentable
end

# app/models/photo.rb
class Photo < ApplicationRecord
  has_many :comments, as: :commentable
end

Foydalanish:

# konsol
article = Article.create(title: "Rails Maslahatlari")
photo = Photo.create(caption: "Go'zal quyosh botishi")

article.comments.create(body: "Ajoyib maqola!")
photo.comments.create(body: "Chiroyli foto!")

Comment.first.commentable # Article qaytaradi
Comment.last.commentable  # Photo qaytaradi

STI va polimorfik aloqalar orasidagi tanlov, ma'lumotlar tuzilmasi va modellarning o'rtasidagi munosabatlarga bog'liq. STI "bir-ani" munosabatlar uchun (Dog bir Animal), polimorfik aloqalar esa "bor" munosabatlar uchun (Article bor Comment, Photo bor Comment, Comment tegishli bo'lishi mumkin Article yoki Photo).

Ruby on Railsda modellarning merosxo'rligi yoki polimorfik aloqalarni qanday amalga oshirish mumkin?