Target Individual Form Instance/Counter Inside A PHP While Loop - php

Question

I have a PDO prepared statement that I use on a single-image page where a user is going to be able to download that specific image. I currently have a counter that increments each time the download button is clicked which updates a counter value in a MySQL database. I'd like to transfer and use the download counter from the single-image page onto an index page that shows multiple images.
Because the form element is inside a while loop when you click the download button, the current functionality updates the counter for all of the images on this page (i.e. everything inside the loop).
Obviously I don't think I can move it outside of the loop because it then won't update anything at all?
How do I get it so the when the download button is clicked for a particular instance of the form, it only updates that specific form elements details?
PHP
<?php
// get username from URL parameter
isset($_GET['username']) ? $username = $_GET['username'] : header("Location: index.php");
// fetch filename details from database
$stmt = $connection->prepare("SELECT * FROM imageposts WHERE username = :username");
$stmt->execute([':username' => $username]);
while ($row = $stmt->fetch()) {
$db_image_filename = htmlspecialchars($row['filename']);
// -- HTML that shows the image file goes here --
// update counter for number of downloads of an image
if (isset($_POST['download'])) {
try {
$sql = "UPDATE imageposts SET downloads = downloads +1 WHERE filename = :filename";
$stmt = $connection->prepare($sql);
$stmt->execute([
':filename' => $db_image_filename
]);
} catch (PDOException $e) {
echo "Error: " . $e->getMessage();
}
}
?>
// download button that updates the counter
<form method="post">
<button type="submit" name="download">Download</button>
</form>
<?php } ?>

Answer 1

One way to approach this is to add some PHP outside of your loop, that references a value from a hidden <form> element inside the loop - in this case you have a $db_image_filename value you could use.
<form method="post">
<button type="submit" name="download">Download</button>
<input type="hidden" name="hidden-filename" value="<?php echo $db_image_filename; ?>">
</form>
Then reference this value in PHP:
<?php
if (isset($_POST['download'])) {
// value from hidden form element
$hidden_filename = $_POST['hidden-filename'];
try {
$sql = "UPDATE imageposts SET downloads = downloads +1 WHERE filename = :filename";
$stmt = $connection->prepare($sql);
$stmt->execute([
':filename' => $hidden_filename
]);
header("location: " . $_SERVER['PHP_SELF']);
} catch (PDOException $e) {
echo "Error: " . $e->getMessage();
}
}
?>