解決策
下記のようにallow_blankを追加したら解決できました
validates :something, allow_blank: true
参考記事
Validate attribute only if it present (only if user fill in it)
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下記のようにallow_blankを追加したら解決できました
validates :something, allow_blank: true
Validate attribute only if it present (only if user fill in it)
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Go to list of users who liked