c# - 对象未设置为对象的实例

Question

我已经为此绞尽脑汁大约一天了，需要一些帮助。我有一个 GridView，我想根据数据库字段更改行的背景颜色。 db 字段为“Inactive”。

这是标记:

<asp:GridView ID="GridView1" runat="server" DataSourceID="WishListDS"  AutoGenerateColumns="false" CssClass="WishListGridView" GridLines="None" OnRowDataBound="WishListGV_RowDataBound">
    <Columns>       
        <asp:TemplateField>
            <ItemTemplate>
                <div class="wlMessage">
                    <asp:Hyperlink ID="ViewHL" runat="server" Text="View" NavigateUrl='<%# "WishListSearchResults.aspx?id=" + Eval("sysid")%>' />
                    <asp:Hyperlink ID="EditHL" runat="server" Text="Edit" NavigateUrl='<%# "WishListEdit.aspx?id=" + Eval("sysid")%>' />
                </div>
                <asp:Hyperlink ID="NameLBL" Runat="server" Text='<%# Eval("customName")%>' NavigateUrl='<%# "WishListSearchResults.aspx?id=" + Eval("sysid")%>' CssClass="wlGVContentTitle" />
                <asp:Label ID="ArrivalLBL" Runat="server" Text='<%# Eval("earliestArrival","{0:d}") + " - " + Eval("latestArrival","{0:d}")%>' CssClass="wlGVContent" />
                <asp:Label ID="StateLBL" Runat="server" Text='<%# Eval("City") + ", " + Eval("State")%>' CssClass="wlGVContent"></asp:Label>
                <asp:HiddenField ID="InactiveHF" runat="server" value='<%# Eval("InActive") %>' />
                <hr />               
            </ItemTemplate>
        </asp:TemplateField>             
    </Columns>
</asp:GridView>

代码如下:

protected void WishListGV_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
       HiddenField hf = (HiddenField)e.Row.FindControl("InActiveHF");
       if (hf.Value == "True")
       {
       }
    }
}

我得到一个错误:

Object reference not set to an instance of an object."

一条线

if (hf.Value == "True")

有人知道为什么会这样吗？

Answer 1

HiddenField 的 Id 在标记和代码中不匹配。使用这个:

HiddenField hf = (HiddenField)e.Row.FindControl("InactiveHF");