default scopeの被害報告

default_scope の被害報告

2015/03/28 minami.rb 最初で最後のLT大会

無量井　健(@muryoimpl)

https://www.flickr.com/photos/jakerust/16827350035

自己紹介

• 無量井　健(むりょうい　けん)

• 永和システムマネジメント 7ヶ月目

• Ruby関西, 関西Ruby会議04・05, るびま etc

• 休日は、低機動型寝たきり二時間サスペンス廃人

皆さんご存知だとおもいますが

https://www.flickr.com/photos/aruarian/2626408619


default_scope

default_scopeclass Item < ActiveRecord::Base default_scope -> { order(:order_no) } end

irb(main)> Item.find(1) SELECT "items".* FROM “items" WHERE "items"."id" = ? ORDER BY “items"."order_no" DESC LIMIT 1 [["id", 1]]

https://www.flickr.com/photos/lintmachine/3652702115

何もしなくても勝手に

条件がつきますねhttps://www.flickr.com/photos/aruarian/2626408619

便利ですね


default_scope の条件外す方法ありますね



unscopedirb(main)> Item.unscoped.find(1) SELECT "items".* FROM “items" WHERE "items"."id" = ? DESC LIMIT 1 [["id", 1]]

irb(main)> Item.unscoped { Item.find(1) } SELECT "items".* FROM “items" WHERE "items"."id" = ? LIMIT 1 [["id", 1]]


exceptirb(main)> Item.except(:order).find(1) SELECT "items".* FROM “items" WHERE "items"."id" = ? DESC LIMIT 1 [["id", 1]]


unscopeirb(main)> Item.unscope(:order).find(1) SELECT "items".* FROM “items" WHERE "items"."id" = ? DESC LIMIT 1 [["id", 1]]

外れましたね？


調べるとだいたいこういう例が

載っていますhttps://www.flickr.com/photos/aruarian/2626408619

さてhttps://www.flickr.com/photos/aruarian/2626408619

結合とかしてたらどうですかね？


includesしてみるぞ

class Author < ActiveRecord::Base has_many :posts

default_scope -> { where(status: :ok) } end

class Post < ActiveRecord::Base belongs_to :author end



includesしてみるぞirb(main)> Post.includes(:author) .where(status: :ok) .where(authors: {name: ‘a’}) SELECT "posts"."id" AS t0_r0, … FROM "posts" LEFT OUTER JOIN "authors" ON "authors"."id" = “posts"."author_id" AND "authors"."status" = ? WHERE "authors"."name" = ? [["status", 1], ["name", "a"]]


unscopedirb(main)> Author.unscoped { Post.includes(:author) .where(status: :ok) .where(authors: {name: ‘a’}) } SELECT "posts"."id" AS t0_r0, … FROM "posts" LEFT OUTER JOIN "authors" ON "authors"."id" = “posts"."author_id" AND "authors"."status" = ? WHERE "authors"."name" = ? [["status", 1], ["name", "a"]]

外れない！https://www.flickr.com/photos/aruarian/2626408619


exceptirb(main)> Post.includes(:author).except(:where) .where(status: :ok) .where(authors: {name: ‘a’}) SELECT "posts"."id" AS t0_r0, … FROM "posts" LEFT OUTER JOIN "authors" ON "authors"."id" = “posts"."author_id" AND "authors"."status" = ? WHERE "authors"."name" = ? [["status", 1], ["name", "a"]]

そもそも ON句だし…



exceptirb(main)> Post.includes(:author) .except(on: :status) #ないよね…無視される .where(status: :ok) .where(authors: {name: ‘a’}) SELECT "posts"."id" AS t0_r0, … FROM "posts" LEFT OUTER JOIN "authors" ON "authors"."id" = “posts"."author_id" AND "authors"."status" = ? WHERE "authors"."name" = ? [["status", 1], ["name", "a"]]


unscopeirb(main)> Post.includes(:author) .unscope(on: :status) #ないよね… .where(status: :ok) .where(authors: {name: ‘a’})

ArgumentError: Hash arguments in .unscope(*args) must have :where as the key.


unscopeirb(main)> Post.includes(:author) .unscope(where: :status) .where(status: :ok) .where(authors: {name: ‘a’}) SELECT "posts"."id" AS t0_r0 … FROM "posts" LEFT OUTER JOIN "authors" ON "authors"."id" = "posts"."author_id" AND "authors"."status" = ? WHERE "authors"."name" = ? [["status", 1], ["name", "a"]]

別の関連つくって…class Author < ActiveRecord::Base has_many :posts


class Post < ActiveRecord::Base belongs_to :author belongs_to :unscoped_author, -> { unscope(where: :status) }, foreign_key: :author_id, class_name: ‘Author’ end https://www.flickr.com/photos/lintmachine/3652702115


別の関連つくって…irb(main)> Post.includes(:unscoped_author) .where(status: :ok) .where(authors: {name: ‘a’}) SELECT "posts"."id" AS t0_r0, … FROM "posts" LEFT OUTER JOIN "authors" ON "authors"."id" = “posts"."author_id" AND "authors"."status" = ? WHERE "authors"."name" = ? [["status", 1], ["name", "a"]]

やはり外れない!


https://www.flickr.com/photos/alvarez-tostado/363243449

マ”マ”ーーー



ということで…



泣きながらこうした…


default_scopes =[]class Author < ActiveRecord::Base has_many :posts


class UnscopedAuthor < Author # ↓ここがポイント self.default_scopes = [] end

class Post < ActiveRecord::Base belongs_to :author belongs_to :unscoped_author, foreign_key :author_id end https://www.flickr.com/photos/lintmachine/3652702115

default_scopeさん…• こんな罠がありました… • 単一モデルしか検索しない間は便利さしか感じないかもしれませんが…SQL的にJOINすることになると面倒なことになります(なりました)

• 少し面倒なクエリを考えるときに直面するのですよ…この問題

• 後悔しないように、scopeを毎回つけるか設計を見直すほうが良いと思います

https://www.flickr.com/photos/71508688@N00/5139944772

default scopeの被害報告

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