Laravel：如何通过键 id 获取单个枢轴行
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Laravel: How to get single pivot row by key id
提问by lesssugar
I have a many-to-many relation set on my Userand NotificationEloquent models. This way I can access the pivot table - user_notifications- as follows:
我在我的User和NotificationEloquent 模型上设置了多对多关系。这样我就可以访问数据透视表 - user_notifications- 如下：
$user = User::find(1);
foreach ($user->notifications() as $n) {
echo $n->pivot->created_at;
}
This will give me all created_atfield values from the pivot table, for the user of ID = 1.
created_at对于 ID = 1 的用户，这将为我提供数据透视表中的所有字段值。
What if I need only onepivot row, let's say the one with notification_id = 2? Is there a way to combine pivotwith whereor has? Can it be done without looping through $user->notifications()?
如果我只需要一个枢轴行，假设是Notification_id = 2 的那个行呢？有没有办法pivot与whereor结合has？可以不循环完成$user->notifications()吗？
回答by lukasgeiter
You can use a whereclause on the relationship:
您可以where在关系上使用子句：
$notification = $user->notifications()->where('notification_id', 2)->first();
echo $notification->pivot->created_at;
回答by AsDh
You can also directly use findmethod.
也可以直接使用find方法。
$notification = $user->notifications()->find(2);
echo $notification->pivot->created_at;
回答by antirealm
I've been dealing with this, and lukasgeiter's answer is fine, until the weird case where you want to find a pivot row by id(if you set up a $table->increments('id')column on the pivot table. I do this sometimes, but a better solution is to use a dedicated model for the relationship (Defining Custom Intermediate Table Models@ https://laravel.com/docs/5.6/eloquent-relationships)
我一直在处理这个问题，lukasgeiter 的回答很好，直到出现你想通过id查找数据透视行的奇怪情况（如果你$table->increments('id')在数据透视表上设置一列。我有时会这样做，但更好的解决方案是为关系使用专用模型（定义自定义中间表模型@ https://laravel.com/docs/5.6/eloquent-relationships）
What you can do in this strange case:
在这种奇怪的情况下你可以做什么：
$notification = $user->notifications()->having('pivot_id', 2)->first();
echo $notification->pivot->created_at;
You'll have to include withPivot('id')in your relationship method in the model. i.e.
您必须withPivot('id')在模型中包含您的关系方法。IE
function notifications() {
return $this->belongsToMany('App\Notification')->withPivot('id');
}
