php Laravel 检查集合是否为空
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Laravel check if collection is empty
提问by Jamie
I've got this in my Laravel webapp:
我在我的 Laravel webapp 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
How could I check if there are any $mentors->intern->employee?
我怎么能检查是否有$mentors->intern->employee？
When I do :
当我做 ：
@if(count($mentors))
It does not check for that.
它不检查。
采纳答案by otezz
You can always count the collection. For example $mentor->intern->count()will return how many intern does a mentor have.
您可以随时计算集合。例如$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
在您的代码中，您可以执行以下操作
foreach($mentors as $mentor)
@if($mentor->intern->count() > 0)
@foreach($mentor->intern as $intern)
<tr class="table-row-link" data-href="/werknemer/{!! $intern->employee->EmployeeId !!}">
<td>{{ $intern->employee->FirstName }}</td>
<td>{{ $intern->employee->LastName }}</td>
</tr>
@endforeach
@else
Mentor don't have any intern
@endif
@endforeach
回答by Drudge Rajen
To determine if there are any results you can do any of the following:
要确定是否有任何结果，您可以执行以下任一操作：
if ($mentor->first()) { }
if (!$mentor->isEmpty()) { }
if ($mentor->count()) { }
if (count($mentor)) { }
if ($mentor->isNotEmpty()) { }
Notes / References
注释/参考
->first()
->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
isEmpty()https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Collection.html#method_isEmpty
->count()
->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($mentors)works because the Collection implements Countable and an internal count() method:
count($mentors)之所以有效，是因为 Collection 实现了 Countable 和一个内部 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()
isNotEmpty()
https://laravel.com/docs/5.7/collections#method-isnotempty
https://laravel.com/docs/5.7/collections#method-isnotempty
So what you can do is :
所以你可以做的是：
if (!$mentors->intern->employee->isEmpty()) { }
回答by Mohamed Salem Lamiri
Starting from Laravel 5.3you can simply use :
从Laravel 5.3开始，您可以简单地使用：
if ($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
回答by Csongor Halmai
This is the fastest way:
这是最快的方法：
if ($coll->isEmpty()) {...}
Other solutions like countdo a bit more than you need which costs slightly more time.
其他解决方案count比您需要的要多一些，这会花费更多的时间。
Plus, the isEmpty()name quite precisely describes what you want to check there so your code will be more readable.
另外，该isEmpty()名称非常准确地描述了您想要检查的内容，因此您的代码将更具可读性。
回答by d.raev
From php7you can use Null Coalesce Opperator:
从php7您可以使用空合并Opperator：
$employee = $mentors->intern ?? $mentors->intern->employee
This will return Nullor the employee.
这将返回Null或员工。
回答by Marcello Patto
I prefer
我更喜欢
(!$mentor)
(!$mentor)
Is more effective and accurate
更有效和准确
