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#Rails で DBに外部キー制約がない場合 has_one と has_many のアソシエーションを両方指定できそうだ #2941

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YumaInaura opened this issue Jan 13, 2020 · 0 comments

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en-translate medium qiita

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YumaInaura commented Jan 13, 2020

You can specify both

class User < ApplicationRecord
  has_one :book
  has_many :books
end

userが持つbookが複数ある場合にhas_oneを見ると、最新のbook一個だけが得られた

user.books.size # 3

user.book # Return latest book instance a user has

YumaInaura added en-translate medium qiita labels

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