Laravel属于ToMany，其中没有一个

问题描述

我有两个表:categories和videos，然后我有一个数据透视表，因为它是一个belongsToMany关系.

I have two tables: categories and videos, I then have a pivot table for these as it's a belongsToMany relationship.

我想做的是将所有视频中没有单个实例归入多个类别之一.

What I'm trying to do is get all of the videos where there isn't a single instance of the video being in one of many categories.

例如

• 视频1属于类别1、2和3.
• 视频2属于类别1和3.
• 视频3属于类别1.

我想获取不在2类或3类中的视频，这意味着它将返回3类视频.

I want to get the video which is NOT in category 2 or 3, meaning this will return Video 3.

到目前为止，我一直在尝试，但没有得到预期的结果，这是因为仍在视频1和2中找到了另一行，就像它们在类别1中一样:

What I've tried so far, which doesn't give the intended result, this is because another row is still found for Video 1 and 2, as they are in Category 1:

Video::whereHas('categories', function($query) {
    $query->whereNotIn('category_id', [2,3]);
})->take(25)->get();

从中填充的查询是:

select * from `videos` where exists (select * from `categories` inner join 
`category_video` on `categories`.`id` = `category_video`.`category_id` where 
`videos`.`id` = `category_video`.`video_id` and `category_id` != ? and 
`category_id` != ? and `categories`.`deleted_at` is null) and `videos`.`deleted_at` 
is null order by `created_at` desc limit 25

推荐答案

您可以使用Eloquent的 whereDoesntHave()约束来获得所需的内容:

You can use Eloquent's whereDoesntHave() constraint to get what you need:

// get all Videos that don't belong to category 2 and 3
Video::whereDoesntHave('categories', function($query) {
  $query->whereIn('id', [2, 3]);
})->get();

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