How to update querystring in C#?

Question

Somewhere in the url there is a &sortBy=6 . How do I update this to &sortBy=4 or &sortBy=2 on a button click? Do I need to write custom string functions to create the correct redirect url?

If I just need to append a query string variable I would do

string completeUrl = HttpContext.Current.Request.Url.AbsoluteUri + "&" + ... Response.Redirect(completeUrl); 

But what I want to do is modify an existing querystring variable.

Answer 1

To modify an existing QueryString value use this approach:

var nameValues = HttpUtility.ParseQueryString(Request.QueryString.ToString()); nameValues.Set("sortBy", "4"); string url = Request.Url.AbsolutePath; Response.Redirect(url + "?" + nameValues); // ToString() is called implicitly 

I go into more detail in another response.

Answer 2

Retrieve the querystring of sortby, then perform string replace on the full Url as follow:

string sUrl = *retrieve the required complete url* string sCurrentValue = Request.QueryString["sortby"]; sUrl = sUrl.Replace("&sortby=" + sCurrentValue, "&sortby=" + newvalue); 

Let me know how it goes :)

Good luck