如何在asp.net的数据列表控件中找到图像控件 [英] how to find image control inside a datalist control in asp.net

问题描述

我有一个数据列表:

Hi, I have a datalist as:

<asp:DataList ID="DataList1" runat="server" RepeatColumns="3" style="z-index: 108; left: 733px; position: absolute; top: 72px" >
          <ItemTemplate><asp:Image ID="uximage" runat="server" /></ItemTemplate>
        </asp:DataList>

我在代码背后编写代码为:

and I am writing code in codebehind as:

protected void Button4_Click(object sender, EventArgs e)
{
  // Image im = (Image)DataList1.FindControl("img");
  Image im = (Image)DataList1.FindControl("uximage");
  im.ImageUrl = "Handler.ashx";
}

我想要的是在该数据列表中找到图像控件
但我收到错误消息

行中的对象引用未设置为对象的实例"

What I want is to find image control in that datalist
but I am getting error as
"object reference not set to an instance of an object" in the line

im.ImageUrl = "Handler.ashx";

我该怎么办?我认为我正在编写正确的代码.请帮忙.

What should I do now? I think that I am writing the correct code. Please help.

推荐答案

foreach(DataListitem item in DataList1.Items)
{
Image im = (Image)item.FindControl("uximage");
im.ImageUtrl = "Handler.ashx";
}

<asp:DataList ID="dataListEmp"  OnItemCommand="DatalistcommandEvent" RepeatColumns="1" CellSpacing="10" GridLines="Both"  ItemStyle-Width="300" ItemStyle-BorderColor="Blue" BorderStyle="Dotted" CellPadding="10"  BorderColor="Blue" runat="server" DataSourceID="sqlDataSourceEmp">

       <ItemTemplate>


       <%# Eval("EmpId") %>
       <%# Eval("Employee Name") %>
        <%# Eval("Location") %>
     <asp:ImageButton runat="server" ID="imgData" AlternateText="Image" CommandName="Myimage" />
       </ItemTemplate>
       </asp:DataList>

受保护的void DatalistcommandEvent(object s，DataListCommandEventArgs e)
{

如果(e.CommandName =="Myimage")
{

DataListItem item = dataListEmp.Items [e.Item.ItemIndex] as DataListItem;
ImageButton imgbtn = item.FindControl("imgData")作为ImageButton;
imgbtn.ImageUrl ="http://localhost:64452/FilesReadAndInsert/Images/dave.jpg";
}

}

protected void DatalistcommandEvent(object s,DataListCommandEventArgs e)
{

if (e.CommandName == "Myimage")
{

DataListItem item = dataListEmp.Items[e.Item.ItemIndex] as DataListItem;
ImageButton imgbtn = item.FindControl("imgData") as ImageButton;
imgbtn.ImageUrl = "http://localhost:64452/FilesReadAndInsert/Images/dave.jpg";
}

}

protected void btnFind_Click(object sender, EventArgs e)
   {
      DataListItem item=dataListEmp.Items[1] as DataListItem;
       ImageButton imgbtn=item.FindControl("imgData") as ImageButton;
       imgbtn.ImageUrl = "http://localhost:64452/FilesReadAndInsert/Images/flow3.jpg";
   }

e.jpg;

上面的方法可以工作，但问题是
在这里，我们必须对项目索引进行硬编码.我们将无法获得正确的索引，这就是我在datalist命令事件中编写的原因

e.jpg";

above will work but the problem is
here we have to hard code the item index. we will not get proper index that''s why i wrote in the datalist command event

DataListItem item=dataListEmp.Items[1] as DataListItem;

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