Asp.net "Global" variables

Question

I'm writing a page in ASP.NET and am having problems following the cycle of initialization on postbacks:

I have (something akin to) the following:

public partial class MyClass : System.Web.UI.Page
{
    String myString = "default";

    protected void Page_Init(object o, EventArgs e)
    {
        myString = Request["passedString"];
        //note that I've tried to set the default here in Init on NULL...
    }

    protected void Page_Load(object o, EventArgs e)
    {
         if(!Postback)
         {
             //code that uses myString....
         }
         else
         {
            //more code that uses myString....
         }
    }
}

And what's happening is that my code picks up the "passedString" just fine, but for some reason, on postback, it resets to the default value - even if I put the assignment of the default in the Page_Init code... which makes me wonder what's going on..

Any help?

Is passedString a form value or querystring? – John Sheehan Mar 27 '09 at 16:28 — John Sheehan, Mar 27 '09 at 16:28

score 4 · Accepted Answer · answered Mar 27 '09 at 16:34

Your class member variables do not live on once the response is sent to the browser. Try using the Session object instead:

public partial class MyClass : System.Web.UI.Page
{    

    protected void Page_Init(object o, EventArgs e)
    {
        Session["myString"] = Request["passedString"];
        //note that I've tried to set the default here in Init on NULL...
    }

    protected void Page_Load(object o, EventArgs e)
    {
         string myString = (string) Session["myString"];

         if(!Postback)
         {
             // use myString retrieved from session here
         }
         else
         {
            //more code that uses myString....
         }
    }
}

"our class member variables do not live on once the response is sent to the browser." Put another way: each postback is working with a NEW instance of your page class. — Joel Coehoorn, Mar 27 '09 at 16:39

score 3 · Answer 2 · edited May 23 '17 at 10:32

3

I feel your pain Matt. I asked a similar question a little while ago:

For a further understanding of the Page Life Cycle check out this question: What is the 'page lifecycle' of an ASP.NET WebForm?

edited May 23 '17 at 10:32

Community

1
1

answered Mar 27 '09 at 16:29

Gavin Miller

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This wasn't exactly what I was looking for, but it was VERY useful information. Thanks! – matthewdunnam Mar 27 '09 at 16:37
Glad I could be of assistance (even if I don't get the accepted answer!) – Gavin Miller Mar 27 '09 at 16:41

Asp.net "Global" variables

2 Answers2

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