Magento 2 – How to print invoices in pdf from frontend (user account)

1. Create your module Vendor_Module
2. Create route app/code/Vendor/Module/etc/frontend/routes.xml

    <?xml version="1.0" ?>
    
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
        <router id="standard">
            <route id="myroute" frontName="myroute">
                <module name="Vendor_Module"/>
            </route>
        </router>
    </config>

3. Create front controller app/code/Vendor/Module/Controller/Getpdf/Invoice.php

<?php
declare(strict_types=1);

namespace VendorModuleControllerGetpdf;

use MagentoFrameworkAppActionHttpGetActionInterface;
use MagentoFrameworkAppRequestInterface;
use MagentoFrameworkAppResponseRedirectInterface;
use MagentoFrameworkAppResponseInterface;
use MagentoFrameworkAppFilesystemDirectoryList;
use MagentoFrameworkControllerResultFactory;
use MagentoSalesModelOrderPdfInvoice as PdfInvoice;
use MagentoFrameworkStdlibDateTimeDateTime;
use MagentoFrameworkAppResponseHttpFileFactory;
use MagentoSalesModelResourceModelOrderInvoiceCollectionFactory;
use MagentoFrameworkMessageManagerInterface;


class Invoice implements HttpGetActionInterface
{
    const SELECTED_PARAM = 'id';

    protected FileFactory $fileFactory;
    protected DateTime $dateTime;
    protected PdfInvoice $pdfInvoice;
    protected RequestInterface $request;
    protected RedirectInterface $redirect;
    protected ManagerInterface $messageManager;
    protected ResultFactory $resultFactory;
    protected CollectionFactory $collectionFactory;

    /**
     * @param DateTime $dateTime
     * @param FileFactory $fileFactory
     * @param PdfInvoice $pdfInvoice
     * @param CollectionFactory $collectionFactory
     * @param RequestInterface $request
     * @param RedirectInterface $redirect
     * @param ManagerInterface $messageManager
     * @param ResultFactory $resultFactory
     */
    public function __construct(
        DateTime          $dateTime,
        FileFactory       $fileFactory,
        PdfInvoice        $pdfInvoice,
        CollectionFactory $collectionFactory,
        RequestInterface  $request,
        RedirectInterface $redirect,
        ManagerInterface $messageManager,
        ResultFactory $resultFactory
    )
    {
        $this->fileFactory = $fileFactory;
        $this->dateTime = $dateTime;
        $this->pdfInvoice = $pdfInvoice;
        $this->request = $request;
        $this->redirect = $redirect;
        $this->messageManager = $messageManager;
        $this->resultFactory = $resultFactory;
        $this->collectionFactory = $collectionFactory;
    }

    /**
     * @return ResponseInterface|MagentoFrameworkControllerResultRedirect|MagentoFrameworkControllerResultInterface
     */
    public function execute()
    {
        try {
            $collection = $this->collectionFactory->create();

            $invoiceId = $this->request->getParam(self::SELECTED_PARAM);
            $filterIds = $invoiceId ? [$invoiceId] : [];
            $collection->addFieldToFilter(
                $collection->getResource()->getIdFieldName(),
                ['in' => $filterIds]
            );

            $pdf = $this->pdfInvoice->getPdf($collection);
            $fileContent = ['type' => 'string', 'value' => $pdf->render(), 'rm' => true];

            return $this->fileFactory->create(
                sprintf('invoice%s.pdf', $this->dateTime->date('Y-m-d_H-i-s')),
                $fileContent,
                DirectoryList::VAR_DIR,
                'application/pdf'
            );
        } catch (Exception $e) {
            $this->messageManager->addErrorMessage($e->getMessage());            
            $resultRedirect = $this->resultFactory->create(ResultFactory::TYPE_REDIRECT);
            $resultRedirect->setUrl($this->redirect->getRefererUrl());
            return $resultRedirect;
        }
    }
}

4. Now you are ready to use this controller. Just create a link and put there href with a path to our controller (In some cases it is a good idea to use MagentoSalesBlockOrderInfo as a class to your block for getting order like $order = $block->getOrder();)

5. Having an order information you can get invoices in your .phtml file

<?php foreach ($order->getInvoiceCollection() as $invoice):?>
    <a href="<?= $block->getUrl('myroute/getpdf/invoice', ['id' => $invoice->getId()]);?>"><?php echo $this->escapeHtml(__('Invoice (PDF)')); ?></a>
<?php endforeach;?>