PHP OnClick file download using file path stored in MySQL

Question

I have searched for quite some time and do not see something which can solve my issue. I'm working on a page which displays a list of files, and when OnClick, user will be allowed to download that file. File path is stored in MySQL to allow for download.
Currently I am using a while loop with SQL query to retrieve and display(echo) the files.

logID = Auto increment ID in MySQL
logDate = DateTime value

fileLink = File path stored in MySQL (E.g C:\www\wamp\file.txt)

while ($row = mysql_fetch_array($result)) {
$ID =$row['logID'];
$date =$row['logDate'];
$file =$row['fileLink'];
echo $ID, ' ';
echo $date, '<br/>';
}

So on screen right now it shows as follows,
1 2014-01-25 09:33:27
2 2014-01-26 09:37:28
3 2014-01-27 09:38:09

I would like to make the date and time which is "echo $date" into a hyperlink (I have trouble on this) which would allow user to download the file on click. I have a code for file download which is,

<?php
if (file_exists($file)) {
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($file));
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: ' . filesize($file));
ob_clean();
flush();
readfile($file);
exit;
}
?>

The issue is when this download code is on the page, the download box appears right away when the page loads, and offers only the option of downloading the file of "2014-01-27" which is the last retrieved item during the SQL while loop.

I have read that the download code should be on another .php file which would be called when it is required, but I am new to PHP and do not really know how to go about doing it.

Primarily my issues are,

How to make the echoed items a hyperlink with onclick event to trigger a download.
How to bind file path to the respective echoed item, as right now $file will store the file path of the last record due to the while loop.
If the above is possible, and the download code is on another .php file, how do I pass the respective $file variable value to that .php file in order for the method to work.

Thank you in advance and appreciate any help given.

David · Accepted Answer · 2014-01-27 16:09:22Z

1

I have read that the download code should be on another .php file which would be called when it is required

That is indeed the case. Thinking of this from a request/response perspective, your PHP code essentially needs to respond to two different kinds of requests:

A request for the list of files
A request for a particular file

These two things would be in two different PHP files. Let's say that the first one is called list.php. It would just show the HTML content for the list of files. It could be something as simple as what you have:

while ($row = mysql_fetch_array($result)) {
    $ID =$row['logID'];
    $date =$row['logDate'];
    $file =$row['fileLink'];

    echo $ID, ' ';
    echo $date, '<br/>';
}

You mention that you want the date to be the hyperlink, correct? Then just surround it with the hyperlink markup. Something like this:

echo '<a href="download.php?id=' . $ID . '">' . $date . '</a>', '<br />';

Notice I did a couple of things here. Not only is the date value now surrounded by a hyperlink, but the hyperlink includes a couple of components:

download.php, which I'm going to assume is the name of the second page. It can be anything you decide, of course.
$ID, which is the value being sent to the second page so it knows which document was clicked. This is a query string value on the URL and would be obtained on the second page by $_GET['id']. NOTE: This value can be changed by the user, do not rely on it as a security measure. Always validate that the user has permission to download the file they've requested on the second page itself.

That second page, download.php, would include the code you have for writing the file to the output. The header information, the file contents, etc. In that page you'd get the ID of the file being requested ($_GET['id']), fetch that one file from the database or the file system or wherever it is, and send it to the user with the code you have.

That way the user is presented with the first page and then can click on any link(s) they want to make request(s) to the second page for the file(s) they want.

answered Jan 27, 2014 at 16:09

David

221k42 gold badges245 silver badges337 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Jethro Over a year ago

Hi David, thank you for the detailed explanation. It was really helpful. And it did work, however with a minor issue. As of now the display is what I stated above with hyperlinks. When I select my last file for download which is "2014-01-27 09:38:09", the download pop up works perfectly. However when I select the other 2 records, it loads the download.php page with text displaying C\:wamp\www\SCS\Logs\2014-01-25.txt or 26.txt respectively. Is there anyway to solve this issue? Thank you once again.

David Over a year ago

@Jethro: It sounds like either that's what those files actually contain, or that your code isn't reading the files correctly and is instead just echoing the name of the file instead of its contents. I'm not really sure what might be causing this (my PHP is very rusty), but to diagnose it you'll want to probably put some logging statements in download.php to get some runtime debugging info. Essentially to make sure each value is what you expect it to be.

Jethro Over a year ago

Hi David, apologies, please ignore my first comment. It is working perfectly fine as I just created another log file for testing. I think the problem which occurred for the first 2 log files for download was due to me manually entering the file path in MySQL, which did not correctly escape and read the directories slashes "\". Thank you very much for the help!

webzar · Accepted Answer · 2014-01-27 16:07:29Z

0

As per your issues 1 and 2:

while ($row = mysql_fetch_array($result)) {
   $ID =$row['logID'];
   $date =$row['logDate'];
   $file =$row['fileLink'];
   echo $ID, ' ';
   echo '<a href="'.$file.'">'.$date.'</a><br/>'; // Hyperlink to file.
}

And for the 3rd issue you can try

  while ($row = mysql_fetch_array($result)) {
       $ID =$row['logID'];
       $date =$row['logDate'];
       $file =$row['fileLink'];
       echo $ID, ' ';
       echo '<a href="yourfile.php?file='.$file.'">'.$date.'</a><br/>';
    }

answered Jan 27, 2014 at 16:07

webzar

1148 bronze badges

Comments

Pavel Galaton · Accepted Answer · 2014-01-27 16:11:50Z

0

As I understand you want to have multiple links that will provide a log file for that particular date.

You should have one file that will prepare list of the log files as an array OR in your while loop do the following:

echo "<a href='download.php?logId={$row['logID']}'>{$row['logDate']}</a>";

Then you should create download.php (your download script that you already have prepared) that will serve file based on logId GET parameter (another query to the database to get filePath).

answered Jan 27, 2014 at 16:11

Pavel Galaton

5931 gold badge6 silver badges10 bronze badges

Collectives™ on Stack Overflow

PHP OnClick file download using file path stored in MySQL

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related