Unable to serialize the session state - asp.net

Question

i am tired wondering the issue for this problem. have read so many blogs and forums for this but i am not able to find out the problem.
I am using "SQLServer" mode to store session.
Everything is working fine. But whenever i use search function in my website, it throws the below error:
"Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted. The same restriction applies if similar serialization is done by the custom session state store in 'Custom' mode."
I am assuming that this is because of the paging code i have used on that page. That code is as below:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
string query = "select xxxxqueryxxxx";
SqlDataAdapter da = new SqlDataAdapter(query, con);
DataSet ds = new DataSet();
try
{
using (con)
{
con.Open();
da.Fill(ds);
}
}
catch
{
ds = null;
}
finally
{
if (ds != null)
{
CustomPaging page = new CustomPaging();
DataTable dt = ds.Tables[0];
page.PageSize = 10;
page.DataSource = dt;
page.CurrentPageIndex = 0;
no = 1;
Session["DT"] = dt;
Session["page"] = page;
bindData(page, dt);
//set these properties for multi columns in datalist
DataList2.RepeatColumns = 1;
DataList2.RepeatDirection = RepeatDirection.Horizontal;
}
}
}
}
void bindData(CustomPaging page, DataTable dt)
{
try
{
DataList2.DataSource = page.DoPaging;
DataList2.DataBind();
//DataList2.DataSource = SqlDataSource1;
//DataList2.DataBind();
lbtnPre.Enabled = !page.IsFirstPage; //Enable / Disable Navigation Button
// lbtnPre.CssClass = "disabledbtn";
lbtnNext.Enabled = !page.IsLastPage;
//lbtnNext.CssClass = "disabledbtn";
lblStatus.Text = NavigationIndicator(); //Build Navigation Indicator
//for creating page index
DataTable dt1 = new DataTable();
dt1.Columns.Add("PageIndex");
dt1.Columns.Add("PageText");
for (int i = 0; i < page.PageCount; i++)
{
DataRow dr = dt1.NewRow();
dr[0] = i;
dr[1] = i + 1;
dt1.Rows.Add(dr);
}
dlPaging.DataSource = dt1;
dlPaging.DataBind();
dlPaging.RepeatColumns = 10;
dlPaging.RepeatDirection = RepeatDirection.Horizontal;
}
catch (Exception)
{
}
finally
{
page = null;
}
}
string NavigationIndicator()
{
string str = string.Empty; //Page x Of Y
str = Convert.ToString(((CustomPaging)Session["page"]).CurrentPageIndex + 1) + " of " + ((CustomPaging)Session["PAGE"]).PageCount.ToString() + " Page(s) found";
return str;
}
protected void lbtnPre_Click(object sender, EventArgs e)
{
int pageIndex = ((CustomPaging)Session["page"]).CurrentPageIndex;
if (!((CustomPaging)Session["page"]).IsFirstPage)
//Decrements the pageIndex by 1 (Move to Previous page)
((CustomPaging)Session["page"]).CurrentPageIndex -= 1;
else
((CustomPaging)Session["page"]).CurrentPageIndex = pageIndex;
//Binds the DataList with new pageIndex
bindData(((CustomPaging)Session["page"]), ((DataTable)Session["DT"]));
}
protected void lbtnNext_Click(object sender, EventArgs e)
{
int pageIndex = ((CustomPaging)Session["page"]).CurrentPageIndex;
if (!((CustomPaging)Session["page"]).IsLastPage)
//Increments the pageIndex by 1 (Move to Next page)
((CustomPaging)Session["page"]).CurrentPageIndex += 1;
else
((CustomPaging)Session["page"]).CurrentPageIndex = pageIndex;
//Binds the DataList with new pageIndex
bindData(((CustomPaging)Session["page"]), ((DataTable)Session["DT"]));
}
protected void DataList2_SelectedIndexChanged(object sender, EventArgs e)
{
Response.Redirect("Default2.aspx?partnumber=" + DataList2.DataKeyField[DataList2.SelectedIndex].ToString());
}
protected void dlPaging_ItemCommand(object source, DataListCommandEventArgs e)
{
if (e.CommandName == "Select")
{
no = int.Parse(e.CommandArgument.ToString()) + 1;
((CustomPaging)Session["page"]).CurrentPageIndex = int.Parse(e.CommandArgument.ToString());
//Binds the DataList with new pageIndex
bindData(((CustomPaging)Session["page"]), ((DataTable)Session["DT"]));
}
}
protected void dlPaging_ItemDataBound(object sender, DataListItemEventArgs e)
{
LinkButton btn = (LinkButton)e.Item.FindControl("lnkbtnPaging");
if (btn.Text == no.ToString())
{
btn.ForeColor = System.Drawing.Color.Maroon;
btn.Font.Underline = false;
}
else
{
btn.ForeColor = System.Drawing.Color.DarkCyan;
btn.Font.Underline = false;
}
}
I just want to know what the problem is in the coding and "how to serialize the session"?
What shold i do to improve the coding?
Any help will be appreciated.
Thank You

Answer 1

I guess your custom paging control is not serializable. This must be the cause of the issue.
Anyway, storing a control in session is not a good idea. Just store the few serializable properties which enable to rebuild the control (PageSize and CurrentPageIndex), or pass them in query string for example.
You could also use ViewState if you can
About storing the DataTable in Session, this might be a really bad idea if you have a lot of data and many connected users.