datalist绑定图片，有请孟子，或高手请进

Question

http://topic.csdn.net/u/20100908/11/903d7344-ab8a-4778-ae4f-3f8199661341.html这次又在一个页面绑定图片，我按照孟子的
 if (e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
        {
            Image image = (Image)e.Item.FindControl("productImg");            System.Data.Common.DbDataRecord d = e.Item.DataItem as System.Data.Common.DbDataRecord;
            if (d["productImg"] == DBNull.Value)
            {
                image.ImageUrl = "~/image/upImage/Default.jpg";
            }
            else
            {
                image.ImageUrl = "~/image/upImage/" + d["productImg"].ToString();
            }
        }错误提示：未将对象引用设置到对象的实例。  System.Data.Common.DbDataRecord d = e.Item.DataItem as System.Data.Common.DbDataRecord;
行 92:             if (d["productImg"] == DBNull.Value)
行 93:             {
行 94:                 image.ImageUrl = "~/image/upImage/Default.jpg";
错误在92行，红色显示。    
纳闷，不知道什么原因

Answer 1

if (e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
  {
  Image image = (Image)e.Item.FindControl("productImg");
  DataRowView drv =e.Item.DataItem as DataRowView ;
  if(drv !=null)  
  {
   image.ImageUrl = Page.Resolveurl("~/image/upImage/Default.jpg"):Page.Resolveurl("~/image/upImage/" + dr["productImg"].ToString());
   }
  }

Answer 2

不可能出现错误的。
按照你aspx描述的，字段名字productSmallImg还是productImg？

Answer 3

这样，把前台代码贴出来：
 <asp:DataList ID="productSortDl"  runat="server" OnItemDataBound="productSortDl_ItemDataBound">
                          <ItemTemplate>
                          <table width="540" border="0" cellpadding="0" cellspacing="0" class="purpleFrame">
                      <tr>
                        <td height="20" background="image/bg6.jpg" bgcolor="#3399ff" class="lv13" style="width: 37px">&nbsp;</td>
                        <td width="451" align="left" background="image/bg6.jpg" bgcolor="#3399ff" class="productsort13"><%# DataBinder.Eval(Container.DataItem,"sortName") %>
                            <asp:Label ID="productSortLb" Text=<%# DataBinder.Eval(Container.DataItem,"sortID") %> runat="server" Visible="false"></asp:Label></td>
                        <td width="50" align="left" background="image/bg6.jpg" bgcolor="#3399ff" class="lv13"><a href="product_more.aspx?sortID=<%# DataBinder.Eval(Container.DataItem,"sortID") %>">
                        <img src="image/more1.gif" width="34" height="9" border="0" /></a></td>
                      </tr>
                      <tr>
                        <td height="130" colspan="3" align="center">
                            <asp:Label ID="Label1" runat="server"></asp:Label>
                            <asp:DataList ID="productDl" runat="server" RepeatDirection="Horizontal">
                      <HeaderTemplate>
                  <table width="500" height="95%" border="0" cellpadding="0" cellspacing="0">
                            <tr>
                      </HeaderTemplate>
                      
                      
                      <ItemTemplate>
                         <td width="125" height="27" align="left" valign="bottom">
                              <table width="100" border="0" cellspacing="0" cellpadding="0">
                                  <tr>
                                    <td height="90" align="center" class="bianlan">
                                    <a href="product_view.aspx?productID=<%# DataBinder.Eval(Container.DataItem,"productID") %>">
                                    <asp:Image ID="productImg"   ImageUrl='<%# DataBinder.Eval(Container.DataItem,"productSmallImg") %>' runat="server" width="95" height="85" border="0"/>
                                    </a></td>
                                  </tr>
                                  <tr>
                                    <td height="22" align="center">
                                    <a href="product_view.aspx?productID=<%# DataBinder.Eval(Container.DataItem,"productID") %>"><%# DataBinder.Eval(Container.DataItem,"productName") %></a></td>
                                  </tr>
                              </table>
                          </td>
                      </ItemTemplate>
                      
                      
                     <AlternatingItemTemplate >
                         <td width="125" height="27" align="left" valign="bottom">
                              <table width="100" border="0" cellspacing="0" cellpadding="0">
                                  <tr>
                                    <td height="90" align="center" class="bianlan">
                                    <a href="product_view.aspx?productID=<%# DataBinder.Eval(Container.DataItem,"productID") %>">
                                    <asp:Image ID="productImg"   ImageUrl='<%# DataBinder.Eval(Container.DataItem,"productSmallImg") %>' runat="server" width="95" height="85" border="0"/>
                                    </a></td>
                                  </tr>
                                  <tr>
                                    <td height="22" align="center">
                                    <a href="product_view.aspx?productID=<%# DataBinder.Eval(Container.DataItem,"productID") %>"><%# DataBinder.Eval(Container.DataItem,"productName") %></a></td>
                                  </tr>
                              </table>
                          </td>
                     </AlternatingItemTemplate>
                     
                      
                      <FooterTemplate>
                            </tr>
                        </table>
                      </FooterTemplate>
                  </asp:DataList>
</td>
                      </tr>
                    </table>
                            <table width="100" border="0" cellspacing="0" cellpadding="0">
                            <tr>
                                <td style="height: 8px">
                                    </td>
                            </tr>
                            </table>
                          </ItemTemplate>
                      </asp:DataList>    
后台：  protected void productSortDl_ItemDataBound(object sender, DataListItemEventArgs e)
    {    if (e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
        {
            Image image = (Image)e.Item.FindControl("productImg");            System.Data.Common.DbDataRecord d = e.Item.DataItem as System.Data.Common.DbDataRecord;
            if (d["productImg"] == DBNull.Value)
            {
                image.ImageUrl = "~/image/upImage/Default.jpg";
            }
            else
            {
                image.ImageUrl = "~/image/upImage/" + d["productImg"].ToString();
            }
        }
       
    }

Answer 4

你的前台不是绑定了吗？
<asp:Image ID="productImg" ImageUrl='<%# DataBinder.Eval(Container.DataItem,"productSmallImg") %>' runat="server" width="95" height="85" border="0"/>
为啥还要在cs再赋值一次呢？当然出错跟这个没关系

Answer 5

是不是这样：这个前台是两个Datalist嵌套，而只是外层的datalist绑定： protected void productSortDl_ItemDataBound(object sender, DataListItemEventArgs e)
  {   

Answer 6

在内层的ItemDataBound中查询image绑定数据

Answer 7

应该在datalist嵌套上出现问题了

Answer 8

嵌套就不能那样找 了Image image = (Image)e.Item.FindControl("productImg");
应该是这个image 为null了

Answer 9

DataList嵌套是可以的。但是ItemDataBound事件里面，不能交叉访问对象的

Answer 10

你应该在里面那个ItemDataBound事件里FindControl;

Answer 11

productDl_ItemDataBound执行以上方法

Answer 12

最外层：
<asp:DataList ID="productSortDl" runat="server" OnItemDataBound="productSortDl_ItemDataBound">里面那个要写(为了明显，改成了AAAA，注意)
<asp:DataList ID="AAAA" runat="server" RepeatDirection="Horizontal" OnItemDataBound="AAAA_ItemDataBound>
后台代码
protected void DataList1_ItemDataBound(object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==ListItemType.AlternatingItem)   
{   
  DataList aa = (DataList)e.Item.FindControl("AAAA");
  aa.DataSurce = GetProductAdminMsg();
  aa.DataBind();
}
}另外一个
protected void AAAA_ItemDataBound(object sender, DataListItemEventArgs e)
{
 if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==ListItemType.AlternatingItem)   
{   
  DataRowView drv = (DataRowView)e.Item.DataItem;  
  Image image = (Image)e.Item.FindControl("productImg");  if (drv["productImg"].ToString() == "")
  {
  image.ImageUrl = @"~/image/upImage/Default.jpg";
  }
  else
  {
  image.ImageUrl = @"~/image/upImage/" + dr["productImg"];
  }
}}

Answer 13

上面的代码都要加
protected void DataList1_ItemDataBound(object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==ListItemType.AlternatingItem)   
{   
  DataList aa = (DataList)e.Item.FindControl("AAAA");
  aa.DataSurce = GetProductAdminMsg();
  aa.DataBind();
}
}
也可以写成
protected void DataList1_ItemDataBound(object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==ListItemType.AlternatingItem)   
{   
  DataList aa = (DataList)e.Item.FindControl("AAAA");
  aa.ItemDataBound +=new DataListItemEventHandler(AAAA_ItemDataBound);  
  aa.DataSurce = GetProductAdminMsg();
  aa.DataBind();
}
}

Answer 14

给你一个嵌套绑定的例子
http://dotnet.aspx.cc/article/f73eeaa9-2bdc-47fd-afd2-59f2fa4897f5/read.aspx

Answer 15

System.InvalidCastException: 无法将类型为“System.Data.Common.DbDataRecord”的对象强制转换为类型“System.Data.DataRowView”。源错误: 
行 116:        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
行 117:        {
行 118:            DataRowView drv = (DataRowView)e.Item.DataItem;
行 119:            Image image = (Image)e.Item.FindControl("productImg"); 
错误在118 ，红色显示

Answer 16

DataRowView drv = (DataRowView)e.Item.DataItem;是错误的改成
System.Data.Common.DbDataRecord d = e.Item.DataItem as System.Data.Common.DbDataRecord;

Answer 17

  protected void productSortDl_ItemDataBound(object sender, DataListItemEventArgs e)
    {  IProduct product = new Product();  if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            DataList aa = (DataList)e.Item.FindControl("productDl");            aa.DataSource  = product.GetProductAdminMsg();
            aa.DataBind();
        }       
    }    protected void productDl_ItemDataBound(object sender, DataListItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            System.Data.Common.DbDataRecord d = e.Item.DataItem as System.Data.Common.DbDataRecord;            Image image = (Image)e.Item.FindControl("productImg");            if (d["productImg"].ToString() == "")
            {
                image.ImageUrl = @"~/image/upImage/Default.jpg";
            }
            else
            {
                image.ImageUrl = @"~/image/upImage/" + d["productImg"];
            }
        }        
    }这样写了，但是前台还是只显示一个图片

Answer 18

你想要的功能是这样的
外层的DataList，显示分类，名称，内层的显示图片列表
productSortDl_ItemDataBound里面应该得到sortId内层的DataList根据这个sortId去读取这个分类下的图片

Answer 19

你好，孟子，问题已经解决，在外层datalist加个 Label lbsortID = (Label)e.Item.FindControl("productSortLb");
然后  if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            DataList aa = (DataList)e.Item.FindControl("productDl");            aa.DataSource = product.GetProductMsgBysortID(Convert.ToInt32(lbsortID.Text));
            aa.DataBind();
        }要学会举一反三那，看来我还是很菜