clearing checkboxlist - asp.net

Question

on my save button i want to clear all values of form i did the following for CheckBoxList beach.
But it doesn't work. Why so, it doesn't make values clear for checkbox list
Branch is filled like this:
protected void course_SelectedIndexChanged(object sender, EventArgs e)
{
try
{
int courseId = Convert.ToInt32(course.SelectedValue);
DataTable dt;
dt = placementManager.GetBranchList(courseId);
if (dt.Rows.Count != 0)
{
Branch.DataSource = dt;
Branch.DataTextField = "branch_name";
Branch.DataValueField = "branch_id";
Branch.DataBind();
}
Btnsave.Visible = false;
GridView1.Visible = false;
}
catch (Exception ex)
{
COMMON.logger.Error("Error on course_SelectedIndexChanged:CompanySelected.aspx.cs", ex);
}
if (b)
{
gridNotExist.Text = "Records Successfully inserted for the displayed table, To insert new records select new entries";
this.ViewState.Remove("selectedList");
this.ViewState.Remove("dt");
Session.Abandon();
passout.SelectedIndex = 0;
company.SelectedIndex = 0;
txtpackage.Text = "";
course.SelectedIndex = 0;
Branch.DataSource = null;
Branch.DataBind();
vistDate.Text = "";
txtvenue.Text = "";
//GridView1.Visible = true;
}
}
aspx page has, of course, branch like this:
<asp:UpdatePanel id="update" runat="server">
<contenttemplate>
<td>
<asp:DropDownList ID="course" runat="server" AutoPostBack="True" OnSelectedIndexChanged="course_SelectedIndexChanged" />
<asp:CustomValidator ID="coursenecessaryForSaveButton" runat="server" ControlToValidate="course" ErrorMessage="Select A Course" OnServerValidate="coursenecessaryForSaveButton_ServerValidate" ValidationGroup="save" />
</td>
<td>
<asp:CustomValidator ID="courseNecessary" runat="server" ErrorMessage="Select A Course" OnServerValidate="courseNecessary_ServerValidate" ValidationGroup="verify" />
</td>
<td style="width: 101px">
Branch Name*
</td>
<td style="width: 126px">
<asp:CheckBoxList id="Branch" runat="server" />
</td>
</contenttemplate>
</asp:UpdatePanel>

Answer 1

<asp:CheckBoxList id="Branch" runat="server" >
is in a different UpdatePanel to the control which is triggering the asynchronous postback - and firing your eventhandler: course_SelectedIndexChanged.
Put the Checkbox List inside the UpdatePanel with id="update" and it will solve your problem.
Still, i would consider refactoring your HTML (and code while you're at it).
For instance - you have two UpdatePanel's - why?
The second one has nothing in it besides checkboxes. The purpose of an UpdatePanel is to dynamically update portions of a page (ie dynamic information) without a full postback.
Having nothing but static controls (checkboxes) inside an UpdatePanel isn't really serving any purpose.
However, my above answer is a stab in the dark at what you're after. You're code-behind code does'nt really make sense:
if (b == true)
Where is b defined??
Branch.DataSource = null
Branch.DataBind()
What are you binding??