Laravel 检查集合是否为空

我的 Laravel 网络应用程序中有这个：

@foreach($mentors as $mentor)
    @foreach($mentor->intern as $intern)
        <tr class="table-row-link" data-href="/werknemer/{!! $intern->employee->EmployeeId !!}">
            <td>{{ $intern->employee->FirstName }}</td>
            <td>{{  $intern->employee->LastName }}</td>
        </tr>
    @endforeach
@endforeach

我怎样才能检查是否有$mentors->intern->employee ?

当我做 ：

@if(count($mentors))

它不检查这一点。

要确定是否有任何结果，您可以执行以下任一操作：

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

注释/参考文献

->first()

https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_first https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_first

isEmpty() https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_isEmpty https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_isEmpty

->count()

https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_count https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_count

count($mentors)之所以有效，是因为 Collection 实现了 Countable 和内部 count() 方法：

https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_count https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_count

isNotEmpty()

https://laravel.com/docs/5.7/collections#method-isnotempty https://laravel.com/docs/5.7/collections#method-isnotempty

所以你可以做的是：

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