的Ruby / Rails的 - 进行自动计算一个模型的属性 [英] Ruby/Rails - Performing automatic calculations for a models attributes

问题描述

进出口工作在轨道创造一个游戏，我遇到了一个问题，创造得分的逻辑。

Im working on creating a game in rails and I ran into a problem for creating the scoring logic.

我有一个模型叫分数属于一个用户，并具有total_points为属性。

I have a model called Score which belongs to a user and has total_points as an attribute.

所以每次用户创建一个职位（或其他）我想自动调整用户total_score属性。

So every time a user creates a post(or whatever) I would like to automatically adjust the users total_score attribute.

我有，我可以在计分模型的地方创建一个方法，但都没有这样做过，所以我有点糊涂了的感觉。

I have a feeling that I could create a method somewhere in the score model but haven't done this before so I'm a bit confused.

推荐答案

这是很好的用例的ActiveRecord的回调。

This is good use case for a ActiveRecord callback.

#post.rb

  belongs_to :score

  after_create :update_total_score

  protected

  def update_total_score
    score.update_attribute :total_score, score.total_score + new_score_value
  end

请注意：如果帖子是可更新的，那么你可能需要使用after_save的，但我的猜测是after_create是你在找什么

Note: if the post is updatable, then you would want to use after_save, but my guess is after_create is what you are looking for

祝你好运！

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