ASP.NET Web Form: Index out of range on redirects.

Question

ASP.NET Web Form: Index out of range on redirects.

Brown, Matt 126

I can get either redirect by themselves to work. If I use both of them, I get an error 'Index was out of range. Must be non-negative and less than the size of the collection.' I even separated the code between page preload and page load functions, and I still get the error.

if (Request.QueryString[0] != null)
{
    Response.Redirect("Request.aspx?id=" + Request.QueryString[0]);
}
else
{
    Response.Redirect("Request.aspx");
}

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Answer 1

Michael Taylor 59,566

We have no real context about what you mean by "redirect by themselves", "get an error index" or "even separated the code between page preload and page load". But just a quick glance at your code it seems like you're trying to include an id query string value as part of your redirect and that code isn't correct. If there is no query string (e.g. http://localhost) then you'll get an OOR error because QueryString is empty. There is no first element.

if (Request.QueryString.Count > 0) {
   Response.Redirect("Request.aspx?id=" + Request.QueryString[0]);
} else {
   Response.Redirect("Request.aspx");
}

I'm assuming here that this code isn't on the actual Request.aspx page. If it was then you'd get an infinite loop.

Brown, Matt 126 Reputation points

2025-05-20T15:26:32.4833333+00:00

What I am saying is the first part of the if statement works by itself. If I add in the other redirect, that one doesn't work. Your solution does work though.

Answer 2

Bruce (SqlWork.com) 76,256 Moderator

Request.QueryString[0] will throw an error if the array is empty. Try:

if (Request.QueryString.Count > 0 && Request.QueryString[0] != null)

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ASP.NET Web Form: Index out of range on redirects.

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