Laravel检查集合是否为空-Laravelcheckifcollectionisempty

10  

You can always count the collection. For example $mentor->intern->count() will return how many intern does a mentor have.

您可以随时统计该集合。例如$ mentor-> intern-> count（）将返回导师有多少实习生。

https://laravel.com/docs/5.2/collections#method-count

https://laravel.com/docs/5.2/collections#method-count

In your code you can do something like this

在你的代码中你可以做这样的事情

foreach($mentors as $mentor)
    @if($mentor->intern->count() > 0)
    @foreach($mentor->intern as $intern)
        
            {{ $intern->employee->FirstName }}
            {{  $intern->employee->LastName }}
        
    @endforeach
    @else
        Mentor don't have any intern
    @endif
@endforeach

33  

To determine if there are any results you can do any of the following:

要确定是否有任何结果，您可以执行以下任何操作：

if ($mentor->first()) { } 
if (!$mentor->isEmpty()) { }
if ($mentor->count()) { }
if (count($mentor)) { }

Notes / References

备注/参考

->first()

- >第一（）

http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_first

http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_first

isEmpty() http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_isEmpty

isEmpty（）http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_isEmpty

->count()

- >计数（）

http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_count

http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_count

count($mentors) works because the Collection implements Countable and an internal count() method:

count（$ mentors）有效，因为Collection实现了Countable和一个内部count（）方法：

http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_count

http://laravel.com/api/5.2/Illuminate/Database/Eloquent/Collection.html#method_count

So what you can do is :

所以你能做的是：

if (!$mentors->intern->employee->isEmpty()) { }

11  

Starting from Laravel 5.3 you can simply use :

从Laravel 5.3开始，您可以简单地使用：

if ($mentor->isNotEmpty()) {
//do something.
}

Documentation https://laravel.com/docs/5.5/collections#method-isnotempty

文档https://laravel.com/docs/5.5/collections#method-isnotempty

5  

This is the fastest way:

这是最快的方法：

if ($coll->isEmpty()) {...}

Other solutions like count do a bit more than you need which costs slightly more time.

像count这样的其他解决方案比你需要的多一点，这需要花费更多的时间。

Plus, the isEmpty() name quite precisely describes what you want to check there so your code will be more readable.

另外，isEmpty（）名称非常准确地描述了您要检查的内容，因此您的代码将更具可读性。

0  

I prefer

我更喜欢

(!$mentor)

（！$导师）

Is more effective and accurate

更有效和准确