获取计数钻上下贯通的关系 [英] Getting count by drilling down through relations

问题描述

我用Rails 4，我希望得到选票的计数为每个岗位审查特定职位。

I'm using Rails 4 and I want to get a count of votes for each individual post review for a given post.

模式：

Post    PostReview    PostReviewVote
id      post_id       post_review_id
        user_id       user_id
                      voted_on_date

我是这样的：

I have something like:

table.table.table-striped.table-hover
  thead
    tr
      th Post Name
      th Reviews Created For Post
      th Total Votes in All Reviews For Post
  tbody
    - for post in @posts
      tr
        td= post.name
        td= PostReview.where(post_id: post.id).size
        td= PostReview.where(post_id: post.id).PostReviewVotes.size

但它不是获取，理由是运行时错误：

But it's not fetching, citing a runtime error:

undefined method `PostReviewVotes' for #<ActiveRecord::Relation []>

有什么建议？我的模型有适当的关联，仅供参考。

Any suggestions? My models have the proper associations, FYI.

推荐答案

您可以简单地做到这一点：

You could simply do this:

post.post_reviews.count
post.post_review_votes.count

如果你把所有的关联定义就像你说的。

If you have all the associations defined as you say.

如果你想有一个方法吧...

or if you want a method for it...

在您的Post模型：

def post_votes_total
  self.post_review_votes.count
end

只要你定义在帖子的关系：

As long as you have defined the relationship in Post:

has_many :post_review_votes, through: :post_reviews

由于要传递@posts变量的观点：

Since you are passing the @posts variable to the view :

post.post_votes_total

使用内置在意见关联方法是好的，但如果逻辑变得更加复杂，你应该使用一个模型方法或一个辅助方法。

Using the built in association methods in the views is fine, but if logic gets more complicated you should really use a model method or a helper method.

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