©2021 Wantedly, Inc. computed_model RailsϞσϧͷpreloadʹடংΛ༩͑Δ Oct 10, 2021 - Masaki Hara (@qnighy ) At Kaigi on Rails _2021_ new 1

©2021 Wantedly, Inc. class User < ApplicationRecord def short_description current_job.then { |c| "#{c.company_name} #{c.position}" } end def current_job jobs.sort { ... }.find { ... } en d end ಈػ Model method 2

©2021 Wantedly, Inc. class User < ApplicationRecord has_many :jobs end users = User.where(...).preload(:jobs).to_ a ಈػ Preload 3

©2021 Wantedly, Inc. users = User.where(...).preload(:jobs).to_ a users.each do |user | sd = user.short_descriptio n .. . end ಈػ Model method + preload 4

©2021 Wantedly, Inc. ੍໿ "DUJWF3FDPSEʹґଘ͠ͳ͍ w ଞϚΠΫϩαʔϏε͔Βऔಘ͢Δ৘ใ΋͋Δ w ෳ਺ιʔε͔Βͷ৘ใͷऔಘ΋ඞཁ ωετͨ͠QSFMPBE 7JFXʹඥ෇͔ͳ͍ w (SBQI2-ͳͲಛఆͷϓϩτίϧʹΑΒͣɺ൚༻తʹ࢖͍͍ͨ 5

©2021 Wantedly, Inc. class User dependency :current_job computed def short_description current_job.then { |c| "#{c.company_name} #{c.position}" } end dependency :jobs computed def current_job jobs.sort { ... }.find { ... } end end ղ๏ .PEFMʹґଘؔ܎Λॻ͘ એݴ͍ͯ͠ͳ͍ґଘؔ܎Λ࢖͏ͱ࣮ߦ࣌ΤϥʔʹͳΔ 6

©2021 Wantedly, Inc. class User include ComputedModel::Mode l dependency :current_job computed def short_description ... en d dependency :jobs computed def current_job ... end end ղ๏ .PEFMʹґଘؔ܎Λॻ͘ %FQFOEFODZ DPNQVUFE͸$PNQVUFE.PEFM.PEFM͔Βར༻Ͱ͖Δ 7

©2021 Wantedly, Inc. users = User.list(user_ids, [:short_description] ) users.each do |user | sd = user.short_descriptio n .. . end ղ๏ ཉ͍͠ϑΟʔϧυΛࢦఆͯ͠ϩʔυ ࢦఆ͍ͯ͠ͳ͍ϑΟʔϧυΛ௚઀࢖͏ͱ࣮ߦ࣌ΤϥʔʹͳΔ 8

©2021 Wantedly, Inc. class User define_primary_loader :raw_user do |subfields, ids: | RawUser.where(id: ids).preload(subfields).map do |raw_user | User.new(raw_user ) end end end ղ๏ σʔλιʔε΋ࣗ෼Ͱॻ͘ ͔ͩΒɺͲΜͳσʔλιʔεʹ΋ద߹͢Δ 9

©2021 Wantedly, Inc. class User define_primary_loader :raw_user { ... } define_loader :books, key: -> { id } do |user_ids, _subfields, ** | BookApi.list(user_id: user_ids).group_by(&:user_id ) end end ղ๏ ෳ਺σʔλιʔε ϚΠΫϩαʔϏε܈͔Β৘ใΛ͔͖ूΊΔͷ΋؆୯ 10

©2021 Wantedly, Inc. ࣾ಺ͷར༻ྫ 6TFSϞσϧ w Ϣʔβʔͷ৘ใʹؔ৺Λ࣋ͭαʔϏε͸ଟ͍ w ͦͷͨΊɺෳ਺ͷϚΠΫϩαʔϏε͔Β৘ใΛ 
 ू໿͢Δඞཁ͕͠͹͠͹ੜ͡Δ ݖݶ؅ཧ w "DUJWF3FDPSEͷϞσϧΛϥοϓͯ͠ɺ 
 ݟ͍͍ͯ৘ใ͚͕ͩϑΟϧλ͞ΕͨϞσϧΛ࡞Δ 11

©2021 Wantedly, Inc. ࣾ಺ͷར༻ྫ γϦΞϥΠβ w ϞσϧͰ͸ͳ͘Ϗϡʔଆʹ࢖ͬͨྫ w 👉QCTFSJBMJ[FSHFN 
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©2021 Wantedly, Inc. ·ͱΊ 1SFMPBE࣌ͷґଘղܾΛ࣮૷ͨ͠ "DUJWF3FDPSEҎ֎ʹ΋ରԠ ෳ਺ϚΠΫϩαʔϏε͔Βͷ৘ใͷू໿ʹ΋࢖͑Δ https://github.com/wantedly/computed_model 13