How to use a session for a variable in all pages

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In my shopping cart project, I use 'Home.aspx' as start page. I use a variable 'v_MyCart' to store the number of products selected for display. To use this variable in all other pages I use a session called as 'Session["mycart"]. The timeout for this session is 20mts. In 'AddToCart.aspx' page the value is incremented by one whenever I click one 'AddToCart button' and is displayed accordingly. But, from 'AddToCart' page if I select 'Home' button the display at 'Home' page becomes zero. I understand that this happens because of line 'Session["mycart"]=v_MyCart;'. If I comment this line and run the project after a gap of 20 mts what happens is , an exception reflects:Object reference not set to an instance of an object.
How to rectify this error, that is, whenever I click the 'Home' button within 20mts of time frame, the value in v_MyCart should not become zero.

C#

public partial class Home : System.Web.UI.Page
{
    static int v_MyCart;

    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["prasiddhiConnectionString"].ConnectionString);
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Session["mycart"] =  v_MyCart;
            v_MyCart = (int)Session["mycart"];
            LblMyCart.Text = Convert.ToString(v_MyCart);
            LblMyCart.Visible = true;

Posted 18-Dec-13 17:04pm

S.Rajendran from Coimbatore

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Rakesh Meel · Answer 1 · 2013-12-18T17:47:00

Solution 2

visit here...

http://msdn.microsoft.com/en-us/library/ms178581.aspx[^]

or

http://stackoverflow.com/questions/8049341/how-pass-session-variables-between-two-or-more-aspx-pages[^]

Posted 18-Dec-13 17:47pm

Rakesh Meel

SarveshShukla · Answer 2 · 2013-12-18T18:19:00

v_mart should not be static and should be a local variable inside page_load method

Make below change in Page_load

C#

int v_Mycart =0;
if (!IsPostBack)
   {
      if(Session["mycart"] !=  null)
        {
            v_MyCart = (int)Session["mycart"];
            
        }

        LblMyCart.Text = Convert.ToString(v_MyCart);
        LblMyCart.Visible = true;
   }

Madhu Nair · Answer 3 · 2013-12-18T17:45:00

Solution 1

After 20 min you are getting object reference error because your session is getting expired. For Session["mycart"] session, instead of assigning session with value from variable v_MyCart variable, directly assign value to the session variable and everything will work smoothly.

Posted 18-Dec-13 17:45pm

Madhu Nair