是否有一种轨道方式来验证实际记录是唯一的而不仅仅是一列？例如,友谊模型/表不应该具有多个相同的记录,例如:
user_id: 10 | friend_id: 20 user_id: 10 | friend_id: 20
validation activerecord ruby-on-rails ruby-on-rails-3 rails-activerecord
activerecord ×1
rails-activerecord ×1
ruby-on-rails ×1
ruby-on-rails-3 ×1
validation ×1