php - Check if variable exist in laravel's blade directive

Question

I'm trying to create blade directive which echo variable (if variable defined) or echo "no data" if variable undefined.

This is my code in AppServiceProvider.php:

<?php

namespace AppProviders;

use Blade;
use IlluminateSupportServiceProvider;


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:

<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)

How could I check inside directives if variable defined?

question from:https://stackoverflow.com/questions/37425978/check-if-variable-exist-in-laravels-blade-directive

Answer 1

Blade has a directive to check if a variable is set:

@isset($var)

@endisset