How to update querystring in C#?

c# asp.net query-string
developer747 picture developer747 · Mar 19, 2012 · Viewed 98.5k times · Source

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

Ahmad Mageed picture Ahmad Mageed · Mar 19, 2012

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.

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