How to check if an image exists and delete it using PHP

Its been almost 8 hours i am struggling with this. I have the code below in my PHP file editAuthor.php that allows me to upload an image among other input fields in a specific directory. In my case this directory is (/uploads/authorAvatars/).

The problem is that when I submit the form and it is already an existing image for the specific author I edit, instead of replace this image with the new I selected in my input type file, it creates a new one and adds it in the directory. So if I click the submit button 5 times it will create 5 images instead of one. The filename of the image is stored in the column "avatar" of the table "authors".

I tried to check with PHP if the input file is not empty so i can unlink the existed image but it doesn't work. I am really out of ideas.

Here is my code:

// Process the uploaded avatar image
if (isset($_FILES['authoravatar']) && $_FILES['authoravatar']['error'] === UPLOAD_ERR_OK ) {
$avatarFile = $_FILES['authoravatar'];
$authorAvatar = isset($author["avatar"]) ? $author["avatar"] : '';
$avatarImage = $avatarDirectory . $authorAvatar;

if ($_FILES['authoravatar']['error'] == 4 || ($_FILES['authoravatar']['size'] == 0 && $_FILES['authoravatar']['error'] == 0)) {
unlink($avatarImage);
}

// Extract the file extension
$fileExtension = pathinfo($avatarFile['name'], PATHINFO_EXTENSION);

// Generate the avatar image filename
$imageFilename = $authorID . "_avatar_" . basename($avatarFile['name']);

// Move the uploaded file to the avatar directory
$destination = $avatarDirectory . $imageFilename;

move_uploaded_file($avatarFile['tmp_name'], $destination);


// Update the avatar database record with the image filename
$stmt = $connection->prepare("UPDATE authors SET avatar = ? WHERE id = ?");
$stmt->bind_param("si", $imageFilename, $authorID);
$stmt->execute();

}

I am literally running out of ideas. Any help would be very much appreciated. Thanks

The condition to delete the existing avatar image file is contingent on the uploaded file being invalid, so unlink will never be called during a successful upload.

$_FILES['authoravatar']['error'] == 4 // no file uploaded (UPLOAD_ERR_NO_FILE)
// or
$_FILES['authoravatar']['error'] == 0 // no error during file upload (UPLOAD_ERR_OK)
$_FILES['authoravatar']['size'] == 0 // uploaded file was empty

The order of operations should ensure that the file was saved successfully as well.

if (isset($_FILES['authoravatar']) && $_FILES['authoravatar']['error'] === UPLOAD_ERR_OK) {
    $avatarFile = $_FILES['authoravatar'];

    // Generate the avatar image filename
    $imageFilename = $authorID . '_avatar_' . basename($avatarFile['name']);

    // Move the uploaded file to the avatar directory
    $destination = $avatarDirectory . $imageFilename;

    $isSaved = move_uploaded_file($avatarFile['tmp_name'], $destination);
    if ($isSaved) {
        // Update the avatar database record with the image filename
        $stmt = $connection->prepare('UPDATE authors SET avatar = ? WHERE id = ?');
        $stmt->bind_param('si', $imageFilename, $authorID);
        $stmt->execute();
        
        // verify pre-existing avatar from Author data
        if (isset($author["avatar"])) {
            $avatarImage = $avatarDirectory . $author['avatar'];
            // ensure a file exists and the directory has permissions
            if (is_file($avatarImage) && is_writable(dirname($avatarImage))) {
                // delete the old avatar image from the filesystem
                unlink($avatarImage);
            }
        }
    }
}

If the intention is to delete the existing avatar image file when the file form field is empty, you would need an additional unlink call.

if (!isset($_FILES['authoravatar']) || 
    UPLOAD_ERR_NO_FILE === $_FILES['authoravatar']['error'] || 
    0 === $_FILES['authoravatar']['size']) {
    // verify pre-existing avatar from Author data
    if (isset($author["avatar"])) {
        $avatarImage = $avatarDirectory . $author['avatar'];
        // ensure a file exists and the directory has permissions
        if (is_file($avatarImage) && is_writable(dirname($avatarImage))) {
            // delete the old avatar image from the filesystem
            unlink($avatarImage);
        }
    }
}