Manipulating DropDownList within TemplateField

I have a dropdownlist inside of a TemplateField, within a GridView.

I would like to dynamically add list items to it and write code to handle w开发者_如何学Pythonhen the index changes. How do I go about manipulating the list, since I can't directly reference the DropDownList when it's in a TemplateField.

Here is my code:

<asp:TemplateField HeaderText="Transfer Location" Visible="false">
   <EditItemTemplate>
      <asp:DropDownList ID="ddlTransferLocation" runat="server" ></asp:DropDownList>
   </EditItemTemplate>
 </asp:TemplateField>

If I'm understanding what you want to do correctly, you can handle adding items to your drop down like this:

foreach (GridViewRow currentRow in gvMyGrid.Rows)
{
    DropDownList myDropDown = (currentRow.FindControl("ddlTransferLocation") as DropDownList);
    if (myDropDown != null)
    {
        myDropDown.Items.Add(new ListItem("some text", "a value"));
    }
}

Then, if you mean handling the index change of the DropDownList you just need to add an event handler to your control:

<asp:DropDownList ID="ddlTransferLocation" runat="server" OnSelectedIndexChanged="ddlTransferLocation_SelectedIndexChanged" AutoPostBack="true"></asp:DropDownList>

Then in that event handler you can use (sender as DropDownList) to get whatever you need from it:

protected void ddlTransferLocation_SelectedIndexChanged(object sender, EventArgs e)
{
    DropDownList myDropDown = (sender as DropDownList);
    if (myDropDown != null) // do something
    {
    }
}