从GridView ASP.net的模板字段内的上载控件中触发JavaScript

Question

I have gridview which contains a column containing a HTMLInput File Control (Upload Button), Also We have an image here, Here is the Code:

   <ItemTemplate>
        <asp:PlaceHolder ID="PlaceHolder1" runat="server" Visible='<%# Bind("IsfileUplo") %>'>
        <div>
        <table>
             <tr>
                 <td>
                  <input id="Upload1" type="file" name="file" onchange="javascript:previewFile(this)" runat="server" accept="image/*" />
                 </td>
             </tr>
         </table>
         </div>
         <div>
            <table>
               <tr>
                 <td>
                  <asp:Image ID="Image2" runat="server" Height="100px" Width="100px" />
                  </td>
                  <td>
                   <asp:Label ID="Label5" runat="server" Text="" Width="120px"></asp:Label>
                  </td>
              </tr>
           </table>
           </div>
    </ItemTemplate>

After running website we have something like this:

As you can see there an Item Template with those controls in each row. Now I need to fire previewFile() javascript function which gets upload button and image ID and then will do something. Here is the code:

        function previewFile() {
            var preview = document.querySelector('#<%=Image2.ClientID %>');
            var file = document.querySelector('#<%=Upload1.ClientID %>').files[0];}

The problem is here, It can not detect Image2 and Upload1 Controls inside Item Template of Grid View. I need to get the image path of selected picture with upload control and show it in image control in client side using this script. But I can not pass correct Control IDs to get it to work.

What should I do?

Answer 1

I change Your onchange="previewFile()" to onchange="previewFile(this)" . It will target specific control (which You clicked) and search inside ItemTemplate ( parentNode of clicked input type="file" ) for first Image control.

aspx :

<ItemTemplate>
     <input id="Upload1" type="file" name="file" onchange="previewFile(this)" runat="server" accept="image/*" />
     <asp:Image ID="Image2" runat="server" Height="100px" Width="100px" />
</ItemTemplate>

js :

function previewFile(ele) {
             var fl = ele.files[0];  //get selected file
             var img = ele.parentNode.getElementsByTagName('img')[0];  //get 1st image control in ItemTemplate where is Your input file is.
             img.src = window.URL.createObjectURL(fl); //preview image without uploading
         }

btw. This is just previewing selected image. It's not uploaded.

Updated : (new code adapted to changed question)

function previewme(ele) {
            var fl = ele.files[0];
            var placeHolder = ele.parentNode.parentNode.parentNode.parentNode.parentNode.parentNode;
            var div = placeHolder.getElementsByTagName('div')[1];
            var tbl = div.getElementsByTagName('table')[0];
            var img = tbl.rows[0].cells[0].getElementsByTagName('img')[0];
            var lbl = tbl.rows[0].cells[1].getElementsByTagName('span')[0];
            img.src = window.URL.createObjectURL(fl);
            lbl.innerHTML = 'File choosed';
        }