Limit Media Library to Given Folder

Question

I have made a plugin that uses the Media Library to allow users to upload files to a specific directory - using the upload_dir filter.

I would like to know if there is a way (i.e. a filter) I can use to limit the media library to displaying only files contained within my custom folder?

If possible, I want the user to be able to choose only files that have been uploaded to the custom folder when interacting with the Media Library instantiated by my plugin.

Answer 1

A solution that works for me is to add a clause to the Wordpress query when the media library is being displayed.

From browsing my Wordpress database I noticed that the full path to wp_posts.post_type = 'attachment' is stored in the wp_posts.guid column.

add_filter('posts_where', 'limitMediaLibraryItems_56456', 10, 2 );
function limitMediaLibraryItems_56456($where, &$wp_query) {
    global $pagenow, $wpdb;

    // Do not modify $where for non-media library requests
    if ($pagenow !== 'media-upload.php') {
        return $where;
    }

    $where .= " AND {$wpdb->posts}.guid LIKE '%my-path-segment%'";

    return $where;
}