ruby-on-rails - Rails 4 - 插入重复的 ActiveRecord 数据

Question

我开发了一些对象，下面是我的代码。

if ObjectRating.where(user_id: current_user.id, object_id: @object.id).present?
    rating = ObjectRating.where(user_id: current_user.id, object_id: @object.id).first
    if rating.update_attributes(rating_params)
      @jsonResult.object = rating
    else
      @jsonResult.status = false
      @jsonResult.message = "Please Retry"
    end 
  else
    rating = @object.object_ratings.new(rating_params)
    rating.user_id = current_user.id

    if rating.save
      @jsonResult.object = rating
    else
      @jsonResult.status = false
      @jsonResult.message = "Please Retry"
    end 
  end 

评分参数是

private
def rating_params
  params.require(:object_rating).permit(:rating)
end

它运行良好，但有时会向数据库中插入重复数据。

---

+----------------------------------------------------------+
| id, object_id , user_id, rating, created_at, updated_at  |
+----------------------------------------------------------+
| 1, 100, 200, 8 ,2015-06-26 10:52:34, 2015-06-26 10:52:48 |
| 2, 100, 200, 8 ,2015-06-26 10:52:34, 2015-06-26 10:52:34 |
| 3, 120, 230, 8 ,2015-06-26 10:54:32, 2015-06-26 10:54:32 |
+----------------------------------------------------------+

---

ID 1, 2 是同一个对象。

我在保存到 Controller 之前检查过，为什么它为下一个创建重复记录？

Answer 1

您可以添加以下列object_id、user_id、rating 的索引。创建迁移，例如，

add_index :object_ratings, [:object_id , :user_id, :rating], unique: true