は関連モデルの特定の属性を検証します

Question

関連モデルの属性を検証する最も簡単な方法は何ですか？

Item 
    belongs_to :user 
    validates_presence_of :user 
    # AND the "is_photographer" column for that user must be true 

User 
    has_many :items 
    # can be a regular user or a photographer 

Answer 1

validate :user_is_photographer, :if => :user 

def user_is_photographer 
    errors.add(:user, "should be a photographer") unless user.is_photographer 
end