Rails的條件驗證拋出未定義的方法型號

Question

所以，我一直工作在一個應用程序（Rails的5），我想確認是否由用戶選擇的屬性（服務器）是我想要的範圍。

class Player < ApplicationRecord 
    validates :nick, presence: true, length: { maximum: 20 } 
    validates :description, length: { maximum: 275 } 
    validates :server, presence: true, if: server_exists? 

    def server_exists? 
    server == "NA" 
    end 

end 

當我試圖訪問localhos：3000我得到以下錯誤：

undefined method `server_exists?' for Player (call 'Player.connection' to establish a connection):Class

有誰知道如何解決它？

謝謝！

Answer 1

You can associate the :if and :unless options with a symbol corresponding to the name of a method that will get called right before validation happens.

與:server_exists?嘗試，而不是server_exists?：

validates :server, presence: true, if: :server_exists? 

Answer 2

您需要使用符號的方法名稱：

http://guides.rubyonrails.org/active_record_validations.html#using-a-symbol-with-if-and-unless

validates :server, presence: true, if: :server_exists?