Dompdf gives me an empty pdf - pdf

Question

I installed dompdf using composer
composer require dompdf/dompdf
in my controller i have this
use Dompdf\Dompdf;
....
function actionPdf() {
$dompdf = new DOMPDF();
$dompdf->loadHtml('<h1>hello world</h1>');
$dompdf->setPaper('A4', 'landscape');
$dompdf->render();
}
but all i get is a blank PDF. When i check app.log i see this
2021-09-02 20:20:41 [127.0.0.1][262][-][error][yii\web\HeadersAlreadySentException] yii\web\HeadersAlreadySentException: Headers already sent in on line 0. in C:\xampp\htdocs\yii2\vendor\yiisoft\yii2\web\Response.php:373
Stack trace:
#0 C:\xampp\htdocs\yii2\vendor\yiisoft\yii2\web\Response.php(346): yii\web\Response->sendHeaders()
#1 C:\xampp\htdocs\yii2\vendor\yiisoft\yii2\base\Application.php(398): yii\web\Response->send()
#2 C:\xampp\htdocs\yii2\frontend\web\index.php(64): yii\base\Application->run()
#3 {main}
Any Idea how to fix this? Thanks

Answer 1

Not sure the exact proper Yii way, but in my case this works:
Note the exit(); at the end.
// instantiate and use the dompdf class
$dompdf_options = new \Dompdf\Options();
$dompdf_options->setDpi(150);
$dompdf = new Dompdf($dompdf_options);
$dompdf->loadHtml($html);
// (Optional) Setup the paper size and orientation
$dompdf->setPaper('A4');
// Render the HTML as PDF
$dompdf->render();
$attachment=false;
$options=[
"Attachment" => $attachment
];
// Output the generated PDF to Browser
$dompdf->stream('Informe de vehículo', $options);
exit();
I guess the problem is caused by how Yii renders the data. But by calling exit() you prevent any of that to happen.