概要
allow_nil
詳細
ActiveRecordで、validation時にallow_nilを利用することでnilを許容します。
サンプル
テーブル定義
CREATE TABLE "articles" ( "id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "title" varchar(255), "text" text, "created_at" datetime, "updated_at" datetime );
Validation
class Article < ActiveRecord::Base has_many :comments, dependent: :destroy validates :title, length: { is: 5 }, allow_nil: true end
試行
rails console(pry)で試行します。
[1] pry(main)> a = Article.new => #<Article id: nil, title: nil, text: nil, created_at: nil, updated_at: nil> [2] pry(main)> a.title = 6 => 6 [3] pry(main)> a.valid? => false [4] pry(main)> a.errors.messages => {:title=>["is the wrong length (should be 5 characters)"]} [5] pry(main)> a.title = nil => nil [6] pry(main)> a.valid? => true [7] pry(main)> a.errors.messages => {}