いつ書いたのか忘れたけど、下書きに書いてあったので公開
次のように、同じモデルに対してdependent: :destroyを設定してしまうと、もとのモデルを削除したときに二重にDELETEが発行されてしまう
class User < ApplicationRecord has_one :latest_post, -> { order(created_at: :desc) }, class_name: 'Post', dependent: :destroy has_many :posts, dependent: :destroy end
user.destroy (0.1ms) begin transaction Post Load (0.3ms) SELECT "posts".* FROM "posts" WHERE "posts"."user_id" = ? ORDER BY "posts"."created_at" DESC LIMIT ? [["user_id", 1], ["LIMIT", 1]] Post Destroy (0.4ms) DELETE FROM "posts" WHERE "posts"."id" = ? [["id", 2]] Post Destroy (0.1ms) DELETE FROM "posts" WHERE "posts"."id" = ? [["id", 1]] Post Destroy (0.1ms) DELETE FROM "posts" WHERE "posts"."id" = ? [["id", 2]] User Destroy (0.1ms) DELETE FROM "users" WHERE "users"."id" = ? [["id", 1]] (0.8ms) commit transaction
dependent: :destroyは片方だけにしておいたほうがよさそう
