How to Set the Correct PHP Headers for PDF File Download: Why Does the Common Approach Fail and How to Fix It?

How to Set the Correct PHP Headers for PDF File Download

Many users encounter difficulties when trying to configure their web applications to automatically open a PDF document when a link is clicked. This article aims to provide a solution to this problem.

A common approach is to employ a redirect to a specific page that generates the necessary headers to initiate the PDF download. However, the following code snippet often fails:

<code class="php">$filename = './pdf/jobs/pdffile.pdf;
$url_download = BASE_URL . RELATIVE_PATH . $filename;
header("Content-type:application/pdf");
header("Content-Disposition:inline;filename='$filename\"");
readfile("downloaded.pdf");</code>

To address this issue, it is recommended to follow the approach demonstrated in Example 2 on w3schools:

<code class="php">header("Content-type:application/pdf");

// Set the desired file name for download
header("Content-Disposition:attachment;filename=\"downloaded.pdf\"");

// Read the PDF content from its source file
readfile("original.pdf");</code>

It is crucial to remember that header() must precede any actual output. In PHP versions 4 and above, output buffering can be employed to circumvent this limitation.

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