囧,老问题了..未将对象引用设置到对象的实例..

Question

后台用实现repeater的<AlternatingItemTemplate>间隔色功能
代码网友给的,如下:
protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            int i = e.Item.ItemIndex % 2; 
            if (i == 0) 
            { 
                //trOrgInfo是repeater的名字
                ((HtmlTableRow)e.Item.FindControl("trOrgInfo")).BgColor = "#ffffff"; //此处报错
            } 
            else 
            { 
                ((HtmlTableRow)e.Item.FindControl("trOrgInfo")).BgColor = "#f9f9f9"; 
            }         }
    }
运行总是跑不起来,一到赋颜色那就报"未将对象引用设置到对象的实例"的错
哪位帮看看怎么改

Answer 1

應該是 HtmlTableRow 沒有實例化吧

Answer 2

e.Item.FindControl("trOrgInfo") 没找到这个控件吧

Answer 3

应该是这样的 
未将对象引用设置到对象的实例
这个问题 其实很好解决 调试 卡那个null 就行了

Answer 4

HtmlTableRow row=(HtmlTableRow)e.Item.FindControl("trOrgInfo");
if(row!=null){
    row.BgColor = "#ffffff"; 
} 

Answer 5

protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            int i = e.Item.ItemIndex % 2; 
            HtmlTableRow htmlTR = (HtmlTableRow)e.Item.FindControl("trOrgInfo");
            if(htmlTR!=null)
            {
             if (i == 0) 
             { 
                //trOrgInfo是repeater的名字
                 ((HtmlTableRow)e.Item.FindControl("trOrgInfo")).BgColor = "#ffffff";
               } 
             else 
             { 
                ((HtmlTableRow)e.Item.FindControl("trOrgInfo")).BgColor = "#f9f9f9"; 
             } 
           }
        }
    }

Answer 6

protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            int i = e.Item.ItemIndex % 2; 
            HtmlTableRow htmlTR = (HtmlTableRow)e.Item.FindControl("trOrgInfo");
            if(htmlTR!=null)
            {
             if (i == 0) 
             { 
                //trOrgInfo是repeater的名字
                 htmlTR.BgColor = "#ffffff";
              } 
             else 
             { 
                htmlTR.BgColor = "#f9f9f9"; 
             } 
           }
        }
    }

Answer 7

发现哪出问题了！！if(htmlTR!=null)到这没进去！！
这是怎么回事啊！

Answer 8

<asp:Repeater runat="server" ID="Repeater1" OnItemDataBound="Repeater1_ItemDataBound">
    <HeaderTemplate><table width="100%" border="0" align="center"><tr></HeaderTemplate>
        <ItemTemplate>
        <td>
                   <a href="../Book/Bookjdshow.aspx?lbid= <%# Eval("ProductId")%>&cs=<%# Eval("MAIN_TYPE_ID")%>" style="color: black;font-weight: bold; font-size:14px;" ><%# Eval("TYPE_NAME")%> </a>
                       <br />
                       <asp:Datalist runat="server" ID="Datalist2" RepeatDirection="Horizontal" RepeatColumns="3">
                            <ItemTemplate>
                                  <a href="../Book/Bookjdshow.aspx?lbid= <%# Eval("ProductId") %>&cs=0" style="font-size:12px;"> 
                            <%# Eval("TYPE_NAME")%></a>&nbsp;&nbsp;
                            </ItemTemplate>
                            <FooterTemplate><a href="#"  style="font-size:12px;">更多>></a></FooterTemplate>
                        </asp:Datalist>
        </td>
        </ItemTemplate>
         <FooterTemplate></tr></table></FooterTemplate>
    </asp:Repeater>
 protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            //实力化Repeater2
            DataList rep = e.Item.FindControl("Datalist2") as DataList;
            //实例化Repeater1的行
            DataRowView rowv = (DataRowView)e.Item.DataItem;
            //取Repeater1行值
            string mainID = rowv["MAIN_TYPE_ID"].ToString();            if (mainID != "")
            {
                //绑定Repeater2数据
                BLLProduct exm = new BLLProduct();
                DataTable dt = exm.selectIndexSub(mainID);//获取从数据。 
                if (dt != null)
                {
                    rep.DataSource = dt;
                    rep.DataBind();
                }
            }
            int j = e.Item.ItemIndex % 2;
            HtmlTableRow htmlTR = (HtmlTableRow)e.Item.FindControl("Repeater1");
            if (htmlTR != null)//<---if内未执行到
            {                if (j == 0)
                {                    htmlTR.BgColor = "#c5e4ff";                }
            }
}
这是完整代码，因为我猜想可能确实是没找到控件repeater1

Answer 9

在Repeater1_ItemDataBound内查询Repeater1肯定不行，字能查询其内部控件或表格,trOrgInfo为行id号，要设置

Answer 10

怎么设置捏？
给td赋Id值？
我试过了 貌似不行
到底怎么才能取到htmlTR啊！~~

Answer 11

<tr id="trOrgInfo" runat="server"></tr>

Answer 12

问题是 我的tr在<HeaderTemplate>里 我一加
id="trOrgInfo" runat="server"就报错 说什么不能跨模板
其他的tr在C# Code里，protected int i = 0;
        //repeater分2列显示
        if (i % 2 == 0 && i > 0)
        {
            e.Item.Controls.Add(new LiteralControl("</tr><tr>"));
        }
        i++;

Answer 13

protected int i = 0;
        //repeater分2列显示
        if (i % 2 == 0 && i > 0)
        {
            if(i%4==0){
                e.Item.Controls.Add(new LiteralControl("</tr><tr style='background-color:#ffffff'>"));
            }else{
                e.Item.Controls.Add(new LiteralControl("</tr><tr style='background-color:#f9f9f9'>"));
            }
        }
        i++;
没试过 猜的

Answer 14

e.Item.FindControl("trOrgInfo") 返回null