php 检查laravel的blade指令中是否存在变量
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Check if variable exist in laravel's blade directive
提问by pupadupa
I'm trying to create blade directive which echo variable (if variable defined) or echo "no data" if variable undefined.
我正在尝试创建刀片指令，该指令回显变量（如果定义了变量）或回显“无数据”（如果变量未定义）。
This is my code in AppServiceProvider.php:
这是我的代码AppServiceProvider.php：
<?php
namespace App\Providers;
use Blade;
use Illuminate\Support\ServiceProvider;
class AppServiceProvider extends ServiceProvider
{
/**
* Bootstrap any application services.
*
* @return void
*/
public function boot()
{
Blade::directive('p', function($ex) {
error_log(print_r($ex,true));
return '<?php $defined_vars = get_defined_vars(); if(array_key_exists(\''. $ex .'\', $defined_vars) ): echo ' . $ex . ' ; else: echo \'no data\'; endif;?>';
});
}
/**
* Register any application services.
*
* @return void
*/
public function register()
{
//
}
}
Here is my index.blade.php:
这是我的 index.blade.php：
<p class="lead">@p($myvar)</p>
But my directive "p" gives "no data" if variable defined.
If I use isset error occurres: Cannot use isset() on the result of an expression (you can use "null !== expression" instead)
但是如果定义了变量，我的指令“p”给出“无数据”。如果我使用isset错误发生：Cannot use isset() on the result of an expression (you can use "null !== expression" instead)
How could I check inside directives if variable defined?
如果定义了变量，我如何检查内部指令？
回答by sanchezcl
Blade has a directive to check if a variable is set:
Blade 有一个指令来检查是否设置了变量：
@isset($var)
@endisset
回答by Ali
You can use in Blade functionality for checking isset i.e
您可以在 Blade 功能中使用来检查 isset，即
{{ $checkvariable or 'not-exist' }}
回答by Connor Leech
Try checking if the variable is empty:
尝试检查变量是否为空：
@if(empty($myvar))
<p>Data does not exist</p>
@else
<p>Your data is here!</p>
@endif
Can also check this thread
也可以检查这个线程
回答by George John
For Laravel 5.7 onwards use.
对于 Laravel 5.7 以后使用。
{{ $checkvariable ?? 'not-exist' }}
{{ $checkvariable ?? 'not-exist' }}
回答by TechPotter
The best and cleanest way check if a variable exists in blade:
检查刀片中是否存在变量的最佳和最干净的方法：
{!! !empty($myvariable) ? $myvariable : 'variable does not exist' !!}
回答by Puneet Verma
For Laravel version >=5.7
对于 Laravel 版本 >=5.7
{{ $value ?? '' }}
For Laravel version <5.7
对于 Laravel 版本 <5.7
{{ $value or '' }}
回答by Jeemusu
What are you trying to pass to your custom directive? If it's just a string/int the following should work.
你想传递给你的自定义指令什么？如果它只是一个字符串/整数，则以下应该有效。
Blade::directive('p', function($expression){
$output = $expression ? $expression : 'nodata';
return "<?php echo {$output}; ?>";
});
In Blade Template
在刀片模板中
@p('Foo')
回答by crishoj
The @emptydirective might be useful:
该@empty指令可能有用：
@empty($var)
$var is unset or false-y
@endempty
回答by Dibyendu Mitra Roy
You can do it in few different ways.
您可以通过几种不同的方式来做到这一点。
Sample-1:
样本 1：
@if( !empty($data['var']))
{{ $data['var'] }}
@endif
Sample-2:
示例 2：
{{ $data['var'] or 'no data found' }}
Sample-3: Using ternary operator
示例 3：使用三元运算符
<a href="" class="{{ ( ! empty($data['var'] ? $data['var'] : 'no data found') }}">
回答by rickslayer
If you trying check a bool variable you can use @unless
如果您尝试检查 bool 变量，则可以使用 @unless
<input type="text" class="@unless ($variable) d-none @endunless" >
<input type="text" class="@unless ($variable) d-none @endunless" >
