Value returning 0

please try this one,

protected void ddlMentor_SelectedIndexChanged(object sender, EventArgs e)
{
    try
    {
        int mentorId = Convert.ToInt32(ddlMentor.SelectedItem.Value)
        GetStudent(mentorId);
    }
    catch (Exception ex)
    {
        Utility.SaveErrorLog(ex.Message, System.IO.Path.GetFileName(Request.Path), System.Reflection.MethodBase.GetCurrentMethod().Name, Convert.ToInt32(hdfLoginCode.Value));
        ShowMessage("Oops...", ex.Message, "error");
    }
}

private void GetStudent(int mentorId)
{
    try
    {

        LMSDBDataContext context = new LMSDBDataContext();
        var Result = (from t2 in context.View_SessionDeliveryCalendarDetails_Students
                       where t2.MentorID == mentorId
                       select new { t2.StudentID,Name=t2.Name + " - " +t2.MobileNo}).Distinct().ToList();
        if (Result != null)
        {
            ddlStudent.DataTextField = "Name";
            ddlStudent.DataValueField = "StudentID";
            ddlStudent.DataSource = Result;
            ddlStudent.DataBind();
            ddlStudent.Items.Insert(0, new ListItem("Select Student", ""));
        }
    }
    catch (Exception ex)
    {
        Utility.SaveErrorLog(ex.Message, System.IO.Path.GetFileName(Request.Path), System.Reflection.MethodBase.GetCurrentMethod().Name, Convert.ToInt32(hdfLoginCode.Value));
        ShowMessage("Oops...", ex.Message, "error");
    }
}

or,

You can do one more thing in page load

//Add below code in your page_load event
if (!IsPostBack)
{
             BinddlMentor(); // This is your Mentor dropdownlist bind method
}

Hi

  What should i change in my code

Thanks

    Select Student

It looks like you are setting the EnableViewState property of the ddlStudent DropDownList to false. This could be the reason why you are getting 0 value in code behind.

When EnableViewState is set to b, the DropDownList's items and their selected values will not be persisted across postbacks. This means that on postback, the DropDownList's selected value will always be the default value (i.e. "0" in your case).

Hi

  Values are getting populated but on code behind it is returning 0

Thanks

Based on the code you provided, it is difficult to determine exactly what is causing the issue. However, there are a few things you can check:

1. Make sure that the ddlMentor_SelectedIndexChanged event is actually being triggered. You can add a breakpoint in the event handler and see if it is being hit.

2. Make sure that the ddlMentor DropDownList is populated with values and that the selected value is not empty or null.

3. Check the data source of the GetStudent() method to ensure that there are actually results returned by the query.

4. Check if there are any errors being thrown in the GetStudent() method that might be causing the DropDownList to not be populated with values.

You can also try debugging the code step by step to see where the issue is occurring.