gridview中的C＃下拉列表未触发选择索引已更改事件Autopostback = true

Question

我已经在下拉菜单中设置了AutoPostBack = true，每次我现在从下拉菜单中选择一个项目时，它都会重新加载页面并将下拉菜单中的项目设置回第一项。当我删除autopostback = true时，这会将值保留在下拉列表中，但不会触发'OnSelectedIndexChanged'事件。我正在尝试将新选择的项目放入一个变量，该变量当前在以下方法中，但是由于某种原因，它不会触发此事件。

protected void Senior_SelectedIndexChanged(object sender, EventArgs e)
{
    GridViewRow gvr = (GridViewRow)(((Control)sender).NamingContainer);
    DropDownList duty = (DropDownList)gvr.FindControl("SeniorDropDownList");
    newseniorinitial = duty.SelectedItem.Text;
    newseniorvalue = duty.SelectedItem.Value;
}

ASPX：

<asp:DropDownList ID="SeniorDropDownList" AutoPostBack="true" runat="server" Visible ="false" OnSelectedIndexChanged="Senior_SelectedIndexChanged"></asp:DropDownList>

上面的下拉代码位于gridview的一列中，并显示在<EditItemTemplate>标记内，并且gridview周围包裹着一个更新面板。为什么我的OnSelectedIndexChanged不会开火？

我的下拉列表正在RowDataBound方法中填充，该方法在以下if语句中填充gridview时调用。

if (e.Row.RowType == DataControlRowType.DataRow && ((e.Row.RowState & DataControlRowState.Edit) > 0))
    {
...(Gets sql data into a datatable then does the following)

     Label seniorlbl = (e.Row.FindControl("SeniorLabel") as Label);
                DropDownList seniorddl = (e.Row.FindControl("SeniorDropDownList") as DropDownList);
                seniorddl.Visible = true;
                seniorlbl.Visible = true;
                seniorddl.DataSource = dt;
                seniorddl.DataTextField = "Initials";
                seniorddl.DataValueField = "SeniorityOrder";
                seniorddl.DataBind();
                seniorddl.SelectedItem.Text = currentinitial;

}

页面加载：

protected void Page_Load(object sender, EventArgs e)
{

    duplicatevalidation.Visible = false;

    if (!Page.IsPostBack)
    {
        GetPivotView();
    }
}

GridView方法：

protected void GetPivotView()
{
    string connectionstring = ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;
    SqlConnection cn = new SqlConnection(connectionstring);
    SqlCommand cmd = new SqlCommand("[dbo].Rota", cn);
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    cmd.CommandType = CommandType.StoredProcedure;

    DataTable ds = new DataTable();
    da.Fill(ds);

    PivotView.DataSource = ds;
    PivotView.DataBind();

}