how to avoid querystring null reference problem

Question

my coding is

if (Request.QueryString["uid"].ToString() != "0")
{
   string dummy  =Request.QueryString["uid"].ToString();
   Label1.Text = dummy;
    Response.Redirect("../Profile/Home1.aspx?uid="+ dummy );
}
else
{
    Label1.Text = "none";
    Session["AccountId"] = 0;
}

my problem is am using in this coding in home page.. if it is the first page in website querystring creates problem.. if the user starts with login page means it works. now i want to avoid the querystring problem.

BrokenGlass · Accepted Answer · 2011-05-07 16:19:42Z

3

you have to fix your if condition to check for null - otherwise you will get an Exception when trying to call ToString() on null:

if(Request.QueryString["uid"] != null &&  Request.QueryString["uid"].ToString() != "0")

But there is a better way to do this - QueryString already returns a string:

if(Request.QueryString["uid"] != null && Request.QueryString["uid"] != "0")

answered May 7, 2011 at 16:19

BrokenGlass

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Colin · Accepted Answer · 2017-03-21 19:42:33Z

0

I know this is old, but for reference.

Request.QueryString[index] returns a string.

The ToString is actually completely redundant, and is causing your problem. (null).toString() results in a null reference exception.

    string uid = Request.QueryString["uid"];
    if (uid != "0") {
        Label1.Text = uid;
        Response.Redirect("../Profile/Home1.aspx?uid="+ uid);
    }
    else {
        Label1.Text = "none";
        Session["AccountId"] = 0;
    }

edited Mar 21, 2017 at 19:42

answered Mar 10, 2016 at 17:23

Colin

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