Change file name for download and start downloading it after click or delay

delay, download, filenames, php

Solution

You will need two parts to do this effectively... In your displayed PHP file (let's call it `download.php`), you'll need to kick off a Javascript function that counts down for your customer to zero. When it reaches zero, it simply redirects to the real download location (let's call it `realdl.php`). This file would actually grab the file content and send it to the user when either redirected or clicked.

Here are some elements you would need in `download.php`:

<? $file_dl_url = "/realdl.php?id=FILEID"; ?>

<script language="javascript">
  var elapsed = 0;
  function countdown {
    // see if 5 seconds have passed
    if (elapsed >= 5) {
      window.location = <?= $file_dl_url ?>;
    } else {
      // update countdown display & wait another second
      elapsed++;
      setTimeout("countdown", 1000);
    }
  }
  setTimeout("countdown", 1000);
</script>

<a href="<?= $file_dl_url ?>">Click Here</a>

Then, all you would need in `realdl.php` is the following:

$file_contents = load_file_from_id($_GET['id']);
$file_name = determine_filename();

header("Content-Disposition: attachment; filename=$file_name");

echo $file_contents;

Of course, you need to provide the methods to get the file contents (either just read from disk or possibly database) as well as to determine the file name. To use time as a filename format, see https://www.php.net/manual/en/function.strftime.php for the `strftime` function.

Depending on how the file is stored, you can be more effective, using `fpassthru` for local files, as an example. You also may want to send the `Content-Length` header if you can determine the file size prior to downloading (i.e. it is static content you are sending).

Problem

Original source

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