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How to set a asp:DropDownList SelectedValue to a Session Variable?

There are several articles describing how to do this is code behind however: 

Is it possible to set the value of a dropdownlist to a session variable on the aspx page? 

I am using SqlDataSource to populate the dropdownlist so do not wish to add code behind if it can be avoided. 

<asp:DropDownList ID="ddl" runat="Server" DataSourceID="sqlDS" DataValueField="ID" DataTextField="TEXT" AppendDataBoundItems="true">
  <asp:ListItem Text="" Value="" Selected="True" />
</asp:DropDownList> 
<asp:SqlDataSource ID="sqlDS" runat="Server" SelectCommand="spDS" SelectCommandType="StoredProcedure" />

Set Session("ID") as selected value on load? 

The dropdown list is already populated from the sqldatasource. I just want to set the initial value on page load.

Last updated:12/22/2014 6:46:40 AM

2 Answers

Pooja Malohtra
Pooja Malohtra

You need a server side code in order to use Session. The following code doesn't requires code behind file, but again the code inside script will run at server side. 

<asp:DropDownList ID="ddl" runat="Server" 
   DataSourceID="sqlDS"
   DataValueField="ID"
   DataTextField="TEXT"
   AppendDataBoundItems="true"
   OnSelectedIndexChanged="ddl_SelectedIndexChanged"
   AutoPostBack="True">
  <asp:ListItem Text="" Value="" Selected="True" />
</asp:DropDownList> 
<asp:SqlDataSource ID="sqlDS" runat="Server"
  SelectCommand="spDS" SelectCommandType="StoredProcedure" /> 
<script runat="server">
    protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
    {
        Session["SelecteValue"] = ddl.SelectedValue;
    }
</script>

Note: Make sure AutoPostBack="True" for DropDownList.

Goti Bandu
Goti Bandu

you'll need an event for your dropdown list on change. Are you using C# or VB.net for your codebehind? 

add to onSelectedIndexChanged="ddl_OnSelectedIndexChanged" 

to your code behind add: 

{this is C# vb is similar} 

protected void ddl_OnSelectedIndexChanged(Object sender, EventArgs e)
{
    Session["selectedID"] = ddl.selectedValue;
}

to your page load, add 

if (isPostback)
{
    ddl.selectedValue = Session["selectedID"];
}

Answer