Modify query string dynamicaly without effecting other

using System.Reflection;
using System.Collections.Specialized;
+++++++++++++++++++++++++++++++++++++++++++++++++++
//Modify the query string at run time
string path = HttpContext.Current.Request.Url.AbsoluteUri;
string[] strarr = path.Split('?');
if (strarr.Length > 1)
{
if (strarr[1].Contains("JobType"))
{
// reflect to readonly property
PropertyInfo isreadonly =

typeof(System.Collections.Specialized.NameValueCollection).

GetProperty("IsReadOnly", BindingFlags.Instance |

BindingFlags.NonPublic);

// make collection editable


isreadonly.SetValue(this.Request.QueryString, false, null);

// modify
this.Request.QueryString.Set("JobType",

Convert.ToString(e.CommandName));

// make collection readonly again


isreadonly.SetValue(this.Request.QueryString, true, null);

Response.Redirect(strarr[0] + "?" +

this.Request.QueryString, false);
}
else
{
Response.Redirect(path + "&JobType=" +

Convert.ToString(e.CommandName), false);
}
}
else
{
Response.Redirect(path + "?JobType=" +

Convert.ToString(e.CommandName), false);
}