Organising WordPress Media Uploads By File Type

Rather than have them scattered among the myriad date-related folders inside WordPress’ Uploads directory, you might sometimes want (or need) to store files according to their type.

Here’s a set of functions to make that possible.

function slikkr_custom_upload_dir($path) {

	$fileext = substr(strrchr($_POST['name'], '.'), 1);
	$dir=NULL;
	$types = array(
		'pdf'   => 'pdf',
		'mp3'   => 'audio'
	);

	if (!empty($path['error']) || ( !array_key_exists($fileext, $types)) ) {
		// These aren't the files you're looking for. He can go about his business.
		return $path;
	}
		
	$dir = (isset($types[$fileext])) ? $types[$fileext] : NULL;

	$path = array(
		'path'      => WP_CONTENT_DIR . '/uploads/' . $dir,
		'url'       => WP_CONTENT_URL . '/uploads/' . $dir,
		'subdir'    => '',
		'basedir'   => WP_CONTENT_DIR . '/uploads',
		'baseurl'   => WP_CONTENT_URL . '/uploads',
		'error'     => false,
	);

	return $path;
}

function slikkr_pre_upload($file) {
	add_filter('upload_dir', array($this, 'slikkr_custom_upload_dir') );
	return $file;
}
	
function slikkr_post_upload($fileinfo) {
	remove_filter('upload_dir', array($this, 'slikkr_custom_upload_dir') );
	return $fileinfo;
}

Initialise the filters and you’re done.

add_filter( 'wp_handle_upload_prefilter', array($this, 'slikkr_pre_upload') );
add_filter( 'wp_handle_upload', array($this, 'slikkr_post_upload') );

— tested and working in version 4.6.1 with no 3rd party themes or plugins installed.