Global Variable loses its value after page index changed in DataGrid

Question

My problem is losing value.I have a DataGrid with standart asp.net pagination. When I change page index, global variable named "id" loses its value. Help me Please.

int id = 0;

void Payments()
{
    radioBtnList = GetData();
    radioBtnList.DataBind();
}

protected void Page_Load(object sender, EventArgs e)
{
    Payments();
    Response.Write(id); //  I get value 0 :(
}

protected void radioBtnList_Changed(object sender, EventArgs e)
{
    id = int.Parse(radioBtnList.SelectedItem.Text);
}

protected void dgw_pagechange(object source, DataGridPageChangedEventArgs e)
{
    dgw.CurrentPageIndex = e.NewPageIndex;
    dgw.DataBind();
}

When you change page, your are posting back to the server to run the dgw_pagechance event. Web apps are stateless. — Wheels73, Jul 17 '18 at 09:02
No.. I'm just saying that the id will lose it's value as you are posting back to the server. — Wheels73, Jul 17 '18 at 09:11
Every request (initial get or postback) is served by a *fresh* instance of the particular Page class. So any class-level values are (re-)initialized. — Hans Keﬆing, Jul 17 '18 at 12:56

score 2 · Answer 1 · answered Jul 17 '18 at 09:14

2

Instead of storing the ID in the page which will be reloaded when the page changes you should store it somewhere that will persist over the postback.

Examples might be:

The session object
A database
A text file

answered Jul 17 '18 at 09:14

SBFrancies

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score 0 · Accepted Answer · answered Jul 18 '18 at 05:38

You can use ViewState like this.

int id = 0;
void Payments ()
{
    radioBtnList = GetData();
    radioBtnList.DataBind ();
}

protected void Page_Load (object sender, EventArgs e)
{
  Payments();
  Response.Write(ViewState["id"]);
}

protected void radioBtnList_Changed (object sender, EventArgs e)
{
   id = int.Parse (radioBtnList.SelectedItem.Text);
   ViewState["id"]=id;
}


protected void dgw_pagechange (object source, DataGridPageChangedEventArgs e)
{
    dgw.CurrentPageIndex = e.NewPageIndex;
    dgw.DataBind();
}

Global Variable loses its value after page index changed in DataGrid

2 Answers2