ServiceStack.HttpUtils.SetQueryParam C# (CSharp) Méthode

        public static string SetQueryParam(this string url, string key, string val)
        {
            if (string.IsNullOrEmpty(url)) return null;
            var qsPos = url.IndexOf('?');
            if (qsPos != -1)
            {
                var existingKeyPos = url.IndexOf(key, qsPos, StringComparison.InvariantCulture);
                if (existingKeyPos != -1)
                {
                    var endPos = url.IndexOf('&', existingKeyPos);
                    if (endPos == -1) endPos = url.Length;

                    var newUrl = url.Substring(0, existingKeyPos + key.Length + 1)
                        + val.UrlEncode()
                        + url.Substring(endPos);
                    return newUrl;
                }
            }
            var prefix = qsPos == -1 ? "?" : "&";
            return url + prefix + key + "=" + val.UrlEncode();
        }