WordPress Restrict Media Library To User Uploads

A quick snippet for your Monday morning that I recently used on a site in development. I needed to restrict the media library items to ones specifically uploaded by that user. In order to do so, I utilized the followed placed in the active themes functions.php file:

// restrict media library to users uploads
add_filter( 'ajax_query_attachments_args', 'show_current_user_attachments' );

function show_current_user_attachments( $query ) {
    $user_id = get_current_user_id();
    if ( $user_id ) {
        $query['author'] = $user_id;
    }
    return $query;
}

Taking this a step further, I also needed to allow subscribers to upload media on the frontend via a post submission form. The following function worked well. I will note that you need to be concerned of security in this situation so necessary steps may need to be taken depending on what kind of application you are building:

add_action('admin_init', 'allow_subscriber_uploads');
function allow_subscriber_uploads() {
    $subscriber = get_role('subscriber');
    $subscriber->add_cap('upload_files');
    $subscriber->add_cap('edit_post');
}