Guido on "Custom upload folder"

Hi,

I want to upload files to an additional upload folder. All files with 'canada' in their name.

I use upload_dir to create a custom upload folder:

function custom_upload_dir( $custom_dir ) {
	$dir = WP_CONTENT_DIR . '/userfiles';
	$url = WP_CONTENT_URL . '/userfiles';

	$bdir = $dir;
	$burl = $url;

	$custom_dir = array(
		'path'    => $dir,
		'url'     => $url,
		'basedir' => $bdir,
		'baseurl' => $burl,
		'error'   => false,
	);
	return $custom_dir;
}
add_filter( 'upload_dir', 'custom_upload_dir' );

Now all uploaded files are listed in the userfiles directory.

So I thought including this does the trick:

$mystring = $_SERVER["REQUEST_URI"];
$findme = 'canada';
$pos = strpos($mystring, $findme);

if ($pos === true) {

But no!

I notice this in codex:

Using this, in conjunction with the wp_handle_upload_prefilter, you can dynamically determine which directory to upload to, based on the files you upload.

But, how can I do that?

Guido