查找关联中所有为零的内容 [英] find all that are nil in the association

问题描述

所以我有一个帖子和一个用户.
帖子有_许多用户，用户属于_一个帖子.
我需要一个 find 来查找所有没有类似以下用户的帖子:

So I have a Post and a User.
Post has_many users and a user belongs_to a post.
I need a find that will find all the Posts that dont have any users like the following:

Post.first.users
 => [] 

推荐答案

Post.where("id not in (select post_id from users)")

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