C# Gridview 标题样式不适用于排序

Question

我不明白为什么 SortedDescendingHeaderStyle-CssClass 和 SortedAscendingHeaderStyle-CssClass 在排序我的 GridView 时被应用到标题？

这是我的标记。我需要在代码隐藏中配置它吗？

.ascending a
    {
        background: url(/images/asc.gif) right no-repeat;
        display: block;
        padding: 0 25px 0 5px;
    }

    .descending a
    {
        background: url(/images/desc.gif) right no-repeat;
        display: block;
        padding: 0 25px 0 5px;
    }

<asp:GridView ID="gvOrderItems" runat="server" GridLines="None" CellSpacing="-1" AutoGenerateColumns="false" SortedAscendingHeaderStyle-CssClass="ascending"
  AllowSorting="true" OnRowDataBound="gvOrderItems_RowDataBound" SortedDescendingHeaderStyle-CssClass="descending" OnSorting="gvOrderItems_Sorting" EnableViewState="true" AllowPaging="true" PageSize="10" OnPageIndexChanging="gvOrderItems_PageIndexChanging1">                       
  <Columns>                             
    <asp:BoundField DataField="OrderDate" HeaderText="Date" HeaderStyle-Font-Underline="true" HeaderStyle-ForeColor="White" ControlStyle-Font-Underline="true" DataFormatString="{0:dd/MM/yyyy}" SortExpression="OrderDate" />
    <asp:BoundField DataField="OrderNumber" HeaderText="Order Number" HeaderStyle-Font-Underline="true" HeaderStyle-ForeColor="White" SortExpression="OrderNumber" />
    <asp:BoundField DataField="SKUNumber" HeaderText="Product Number" HeaderStyle-Font-Underline="true" HeaderStyle-ForeColor="White" SortExpression="SKUNumber" />
    <asp:BoundField DataField="OrderItemSKUName" HeaderText="Product Description" />
    <asp:BoundField DataField="mtrx_Code2" HeaderText="Size" />
    <asp:BoundField DataField="OrderItemUnitCount" HeaderText="OTY" />
    <asp:BoundField DataField="OrderItemStatus" HeaderText="Status" />        
  </Columns>
  <PagerStyle HorizontalAlign="Right" CssClass="cssPager"/>    

</asp:GridView>

Answer 1

感谢 ConnorsFan，我得以解决这个问题。基本上遍历列并匹配请求的排序表达式以获得列的索引。这是我的解决方案

foreach (DataControlField col in gvOrderItems.Columns)
{
    if (col.SortExpression == sortExpression)
    {
      int index = gvOrderItems.Columns.IndexOf(col);
      gvOrderItems.Columns[index].HeaderStyle.CssClass = "descending"; 
    }
}