Why is app undefined when called from controller?

Question

I wonder why I can't access $app from my controllers.

I'm using this service provider that I register in app.php.

$app->register(\Barryvdh\DomPDF\ServiceProvider::class);

The documentations tells me to use it as follows (from a controller):

$pdf = $app->make('dompdf.wrapper');
$pdf->loadHTML('<h1>Test</h1>');
return $pdf->stream();

or:

$pdf = App::make('dompdf.wrapper');
$pdf->loadHTML('<h1>Test</h1>');
return $pdf->stream();

Either way gives me the following error

Undefined variable: app

How can I make this work?

Answer 1

In Lumen you should use the app() helper method (see Lumen docs) to get an instance of a class.

Here is an example, that I used.

routes/web.php

<?php

/** @var \Laravel\Lumen\Routing\Router $router */

$router->get('/', 'ExampleController@index');

app/Http/Controllers/ExampleController.php

<?php

namespace App\Http\Controllers;

use Dompdf\Dompdf;

class ExampleController extends Controller
{
    public function index()
    {
        /** @var Dompdf $pdf */
        $pdf = app('dompdf');
        $pdf->loadHTML('<h1>Test</h1>');

        // Output whatever you like
        return $pdf->outputHtml();
    }
}