Magento 2 : Button Onclick Method Executed Before Button is Clicked

Question

I got following code:

<?php
namespace UV\PrintBestellschein\Block\Adminhtml;
use Magento\Framework\App\Filesystem\DirectoryList;
class PrintBestellscheinButton extends \Magento\Backend\Block\Widget\Container
{

    protected $coreRegistry = null;
    public function __construct(
        \Magento\Backend\Block\Widget\Context $context,
        \Magento\Framework\Registry $registry,
        \UV\Bestellung\Model\Order\Pdf\Shipment $pdfGenerator,
        array $data = []
    ) {
        $this->pdfGenerator = $pdfGenerator;
        $this->coreRegistry = $registry;
        parent::__construct($context, $data);
    }

    protected function _construct()
    {
        $this->addButton(
            'uv_printbestellschein',
            [
                'label'   => 'Bestellschein drucken',
                'class'   => 'print',
                'onclick' => 'setLocation(\'' . $this->startDownload() . '\')'
            ]
        );

        parent::_construct();
    }

    public function startDownload() {

        $objectManager =  \Magento\Framework\App\ObjectManager::getInstance();
        $order = $objectManager->create('Magento\Sales\Model\Order')->load($this->getOrderId());

        if($order->hasShipments()) {
            #Sendungen vorhanden
            $shipments = $order->getShipmentsCollection();
            $content = $this->pdfGenerator->getPdf($shipments);
            $fileFactory = $objectManager->get('\Magento\Framework\App\Response\Http\FileFactory');
            $fileFactory->create('packing-slip.pdf', $content->render(), DirectoryList::VAR_DIR , 'application/octet-stream'); 

        } else {
            #Keine Sendungen vorhanden
        }
    }

    public function getOrderId()
    {
       return $this->coreRegistry->registry('sales_order')->getId();
    }
}

The button is successfully added to

sales_order_grid

When I click on an order it starts download, which only should start when I press the button.

Why is that happening? Thanks!

Answer 1

In your button definition replace onclick with on_click