How to return PDF files in Symfony

Overview

In the world of web applications, there are often needs for generating and delivering files in various formats; a common format is PDF. Symfony, being a robust framework for building web applications in PHP, has several ways of dealing with this requirement. In this guide, we’ll embark on the journey of how to return PDF files as responses in a Symfony application.

Introduction to Symfony’s Response Class

Symfony’s HTTPFoundation component provides a powerful abstraction for handling HTTP requests and responses. Amongst other things, it allows you to create various types of responses, including binary file responses suitable for PDF files. The most straightforward way to return a file is using the BinaryFileResponse class.

Generating Your PDF

Before returning a PDF, you will need to generate one. You could create a PDF from scratch using a library like TCPDF or FPDF. A more practical method, especially when working with HTML templates, is to leverage a HTML to PDF converter library like KnpSnappyBundle or Dompdf. Once you’ve added your chosen PDF generation library to your project via Composer, you are ready to create your PDF.

Here’s how you could generate a PDF using KnpSnappyBundle:

use Knp\Snappy\Pdf;

$snappy = new Pdf('/usr/local/bin/wkhtmltopdf');

// You can pass previously rendered HTML to this method
$html = $this->renderView('your_template.html.twig', ['some' => 'data']);
$pdfContent = $snappy->getOutputFromHtml($html);
// Now you have your PDF content in $pdfContent variable

Returning a PDF Response

Once you have your PDF generated, returning it as a response is straightforward:

use Symfony\Component\HttpFoundation\BinaryFileResponse;

public function downloadPdfAction()
{
    // Assuming you've saved the PDF at $pdfPath
    $pdfPath = $this->getParameter('pdf_directory').'/file.pdf';

    return new BinaryFileResponse($pdfPath);
}

Setting the Content-Disposition Header

To force the browser to download the PDF rather than displaying it, you set the Content-Disposition header to ‘attachment’.

use Symfony\Component\HttpFoundation\BinaryFileResponse;
use Symfony\Component\HttpFoundation\ResponseHeaderBag;

public function downloadPdfAction()
{
    $pdfPath = $this->getParameter('pdf_directory').'/file.pdf';
    $response = new BinaryFileResponse($pdfPath);
    $response->setContentDisposition(
        ResponseHeaderBag::DISPOSITION_ATTACHMENT,
        'filename.pdf'
    );

    return $response;
}

The above code, when a user accesses the related URL, will prompt a download with the filename ‘filename.pdf’.

Streamed Responses

In case you want the PDF to be generated on the fly while the user is downloading it, Symfony has a StreamedResponse. This is especially useful for large files or when the PDF generation process is resource-intensive.

use Symfony\Component\HttpFoundation\StreamedResponse;

public function streamPdfAction()
{
    $response = new StreamedResponse(function () {
        // This is where the PDF generation logic goes
        // You can echo the PDF content here
        // This example uses the KnpSnappyBundle
        $snappy = new Pdf('/usr/local/bin/wkhtmltopdf');
        $html = $this->renderView('your_template.html.twig', ['some' => 'data']);
        $pdfContent = $snappy->getOutputFromHtml($html);
        echo $pdfContent;
    });

    $response->setStatusCode(Response::HTTP_OK);
    $response->headers->set('Content-Type', 'application/pdf');
    // This will suggest saving the PDF as 'filename.pdf'
    $response->headers->set('Content-Disposition', 'attachment; filename="filename.pdf"');

    return $response;
}

Conclusion

This guide has shown you multiple ways to return a PDF file within a Symfony application, whether it’s pre-generated and saved on the server or generated dynamically on request. When serving files, always consider the security implications and ensure that you validate permissions appropriately to prevent unauthorized access to files.

Remember to take advantage of Symfony’s features to structure your code in a way that is both efficient and easy to read. With the right library to generate PDFs and the Symfony’s HTTPFoundation component, you can build a robust solution for handling file downloads in your application.