如果我正确理解了问题，您应该能够按用户id查询媒体。类似以下（未测试）代码：

//only do this if there is a user logged in
if( is_user_logged_in() ) {

    //get the currenly logged in user
    $user_ID = get_current_user_id();

    $upload_args = array(
        \'post_type\' => \'attachment\',
        \'author\' => $user_ID
    );

    $uploads = new WP_Query( $upload_args );
}else{
    //what to do if there is no user logged in.
}