覚書: Rails: ポリモーフィック関連のスキャフォールド

ruby 3.1.2p20
Rails 7.0.2.4
Bundler version 2.3.14

Railsガイド 2.9 ポリモーフィック関連付け
Rails 7 API: ActiveRecord::FixtureSet（翻訳）

gem install bundler -v "2.3.14"
rails new many_pict_app && cd many_pict_app
bin/rails g scaffold Product name
bin/rails g scaffold Employee name
bin/rails g scaffold Picture name imageable:belongs_to{polymorphic}
bin/rails db:migrate

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable
class Product < ApplicationRecord
  has_many :pictures, as: :imageable

# test/fixtures/pictures.yml
# Employee one が Picture を1つ持つ。
# Product one が Picture を2つ持つ。

employee_pict_1:
  name: Employee Pict 1
  imageable: one (Employee)

product_pict_1:
  name: Product Pict 1
  imageable: one (Product)

product_pict_2:
  name: Product Pict 2
  imageable: one (Product)

bin/rails db:fixtures:load
bin/rails c

Picture.order(:name).pluck(:imageable_type, :imageable_id)
# e.g, => [["Employee", 980190962], ["Product", 980190962], ["Product", 980190962]]
# ※今回は Employee と Product の fixture がどちらも one なのでIDが同じになっている。
# imageable_type で所属先を判別できる。

Picture.first.imageable #  e.g, => #<Product:...

Employee.first.pictures # => 1
Employee.first.pictures.first.name # => "Employee Pict 1"
Product.first.pictures.count # => 2
Product.first.pictures # => ...

以上です。