按钮内部网格值未返回更新值onclick事件

Question

我在网格中的Button内有一个ItemTemplate。我正在动态分配按钮文本。因为我需要为每个行按钮提供不同的文本。但OnClick事件未显示更新的文本，而是显示空字符串。请帮忙！！

<asp:TemplateField HeaderText="GetHistory">
    <ItemTemplate>
        <asp:Button 
            DataField="GetHistory" 
            ID="btn_getHistory" 
            CausesValidation="false" 
            runat="server" 
            OnClick="btn_getHistory_Click" Visible="false" />
    </ItemTemplate>
 </asp:TemplateField>




  protected void btn_getHistory_Click(object sender, EventArgs e)
    {
     //My sender text is showing empty here
    }


  protected void GridViewTree1_RowCreated(object sender, GridViewRowEventArgs e)
  {
 if (e.Row.RowType == DataControlRowType.DataRow && e.Row.DataItem != null && !((System.Data.DataRowView)(e.Row.DataItem)).Row.ItemArray[0].ToString().Contains("\\"))
            {

                Button btn_getHistory = (Button)e.Row.Cells[3].FindControl("btn_getHistory");
                if (btn_getHistory != null)
                {
                    btn_getHistory.Visible = true;

                    var chunks = ((System.Data.DataRowView)(e.Row.DataItem)).Row.ItemArray[0].ToString().Split('_'); // any separator characters
                    var a = chunks.Take(chunks.Length - 1);
                    string testsetName = string.Empty;
                    foreach (string b in a)
                    {
                        testsetName = testsetName + b + '_';
                    }


                    btn_getHistory.Text = testsetName.ToString().TrimEnd('_');
                }
   }