Asp.net file upload with overwrite confirmation

Question

User-574920078 posted

Hi,

I am using asp:fileupload for uploading files. I want to be able to check if the file already exists in the upload folder and ask the user if he/she wants to overwrite the existing file. How can I accomplish this? 

Answer 1

User535736832 posted
you can achieve this using javascript.
try this

<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="Button1" runat="server" Text="Submit" OnClick="button1_click" />
<input type="hidden" runat="server" id="hfFileExists" value="0" />
<input type="hidden" runat="server" id="hfFileExistsConfirm" value="" />
<input type="hidden" runat="server" id="hfPostedFileName" value="" />

<!-- this script should be placed at the end of form -->
<script language="javascript" type="text/javascript">
if(document.getElementById("hfFileExists").value=="1")
{
      if(confirm("File already exists. Do you want to overwrite"))
        document.getElementById("hfFileExistsConfirm").value = "Yes";
     else
       document.getElementById("hfFileExistsConfirm").value = "No";

     document.getElementById("hfFileExists").value="0";
     document.forms[0].submit();
}
</script>

C# Code behind

protected void Page_Load(object sender, EventArgs e)
{
   if (IsPostBack)
   {
      if (hfFileExistsConfirm.Value.ToLower() == "yes")
      {
         hfFileExists.Value = "0";
         hfFileExistsConfirm.Value = "";
         //upload file copy from temp location that we have saved on button click
        System.IO.File.Copy("C:\\temp_" + hfPostedFileName.Value, "C:\\" + hfPostedFileName.Value, true);
     }
  }
}

protected void button1_click(object sender, EventArgs e)
{
     String ServerPath = "C:\\";
     if (System.IO.File.Exists(ServerPath + FileUpload1.FileName))
     {
         hfFileExists.Value = "1";
         hfFileExistsConfirm.Value = "";
         hfPostedFileName.Value = FileUpload1.FileName;
         FileUpload1.PostedFile.SaveAs("C:\\temp_" + FileUpload1.FileName); //Save temporary to some other location then if user selects to overwrite file we can copy that file from this location
     }
     else
     {
        //Upload File
         FileUpload1.PostedFile.SaveAs("C:\\" + FileUpload1.FileName);
      }
}

Hope it helps, let me know in case of any queries

Answer 2

User-574920078 posted
Thanks for the reply. The approach you used requires that the file is still uploaded to a temporary location on the server even if the user later decided to cancel the operation. I would like to be able to prevent that unnecessary overhead.

Answer 3

User535736832 posted
Ok.. I got it.
Let's use AJAX to solve this.

Javascript
<script type ="text/javascript">
function CheckFileExists()
{
    PageMethods.CheckFileExists(document.getElementById('FileUpload1').value,FileExistsCallBack);
    return false;
}

 

function FileExistsCallBack(result)
{
     if(result) //if file exists on server, confirm with user
     {
        if(confirm("File already exists. Do you want to overwrite"))
             __doPostBack('button1','');
    }
    else
        __doPostBack('button1',''); //file doesn't exists on server.. So upload it
}
</script>

<asp:ScriptManager runat="server" ID="ScriptManager1" EnablePageMethods="true" />
<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="Button1" runat="server" Text="Submit" CausesValidation="true" OnClientClick="return CheckFileExists()" OnClick="button1_click" />

C# Code behind

protected void button1_click(object sender, EventArgs e)
{
    String ServerPath = "C:\\";
    FileUpload1.PostedFile.SaveAs(ServerPath + FileUpload1.FileName);
}

[System.Web.Services.WebMethod]
[System.Web.Script.Services.ScriptMethod]
public static Boolean CheckFileExists(String FileName)
{
    String ParseFileName;
    ParseFileName = FileName.Substring(FileName.LastIndexOf("\\") + 1);
    if (System.IO.File.Exists("C:\\" + ParseFileName))
       return true;
    else
        return false;
}

Hope it will be helpful. Well i have tested on my PC and its working as you wanted. enjoy!!!

Answer 4

User-485743180 posted

Hi,

Neither overwrite nor upload happens when used with ScriptManager and UpdatePanel... Whats the reason and solution behind this..

Answer 5

User1051635487 posted

Hi Iam using the code that you wrote once I click on OK the file is getting saved in the temporary folder instead of the c:\\ folder. how can I copy the existing file from temp to c? and replace the existing one???

Answer 6

User-43865706 posted

hi,

i have followed the script but its not working on tabpanel

am using ajaxtoolkit for tabpanel the script is not working with tabpanels 

any solution for that???

thanks inadvance

Answer 7

User1138998628 posted

Then check if the file exists before you do the upload.

// Specify the path to save the uploaded file to.
string savePath = "c:\\project\\uploads\\";

// Get the name of the file to upload.
string fileName = FileUpload1.FileName;

// Create the path and file name to check for duplicates.
string pathToCheck = savePath + fileName;

// Check to see if a file already exists with the same name as the file to upload.        
        if (System.IO.File.Exists(pathToCheck)) 
        {
          //same file exists do something before it is overwritten
        }

 

Answer 8

User1138998628 posted

you can write it in javascript

Add client-side script to a Button, LinkButton, or ImageButton s client-side onclick event can be accomplished through the use of the OnClientClickproperty

<asp:Button ID="Button" runat="server" OnClientClick="return confirm('Are you certain you want to do what you want to do?');">
</asp:Button>

Answer 9

User-43865706 posted

hi

i used this  code its working