英文:
In ruby rails, is there a method to get the objects outside of a where method's scope?
问题
对于上下文，基本上我正在尝试找出哪些用户没有某篇帖子，例如：
@specified = User.joins(:post).where(post: {content: "Goodbye!"})
与我想要获取的内容（基本上只是未包括在内的每个用户）：
!@specified
我尝试否定它，但显然不起作用，有解决方法吗？
英文:
For context, basically Im trying to find out which Users don't have a certain post, for example:
@specified = User.joins(:post).where(post: {content: "Goodbye!"})
vs. what I want to get (which is basically just every user that wasnt included)
!@specified
I tried negating it but it doesn't work apparantly, Is there a solution to this?
答案1
得分: 1
这会导致重复的用户，如果用户有多个帖子，并且跳过没有帖子的用户：
User.joins(:post) # 应该是 :posts 吗？
你找到了不想要的内容：
User.joins(:post).where(post: {content: "Goodbye!"})
not 只过滤掉帖子中包含 "Goodbye!" 的帖子，如果用户有其他帖子，这个用户将包含在结果中：
User.joins(:post).where.not(post: {content: "Goodbye!"})
简单的方法是否定整个条件：
User.where.not(
id: User.joins(:post).where(post: {content: "Goodbye!"})
)
英文:
This will give you duplicate users if user has more than one post and skip users without posts:
User.joins(:post) # should it be :posts?
You found what you don't want:
User.joins(:post).where(post: {content: "Goodbye!"})
not only filters out the post that has "Goodbye!", if a user has other posts, this user will be included in the result:
User.joins(:post).where.not(post: {content: "Goodbye!"})
Easy way out is to negate the whole thing:
User.where.not(
id: User.joins(:post).where(post: {content: "Goodbye!"})
)
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