public static String AppendQueryString( this string url, Object parameters ) { if(String.IsNullOrEmpty(url)) throw new ArgumentNullException("url", "url can't be empty"); string query = parameters.ToQueryString(); if(String.IsNullOrEmpty(query)) return url; StringBuilder builder = new StringBuilder(); builder.Append(url); if(url[url.Length - 1] != '?') builder.Append('?'); builder.Append(query); return builder.ToString(); }