Question

This is related to my previous question. An unforeseen issue arose with the Wizard control.

I now know how to upload to FTP, however when using the FileUpload control inside a Wizard control, when you move to the next step, the File you selected gets cleared because of the postback. I need to be able to rename the file according to the results from the Wizard before uploading. So…

1. I finish my wizard
2. It uploads some stuff to a database
3. Renames the file according to those results
4. Uploads the renamed file to the FTP server

I suspect I will need to follow a procedure something like this, having an upload button next to FileUpload

1. On “Upload” button click stream the file to the Web Server.
2. Complete the Wizard.
3. If the wizard completes successfully, rename file and stream to FTP server.
4. If the wizard fails, what? Delete the file from the web server? How?

I think I understand the process, so I would like help on how to split my FTP Upload function into two parts with the proper error handling for when the wizard fails.

It would be a great help if you please use the following code as a base. Thanks as always 🙂

Protected Sub UploadFile(ByVal NewFilename As String)
    Dim myFtpWebRequest As FtpWebRequest
    Dim myFtpWebResponse As FtpWebResponse

    'Function one? - Problem, "NewFilename" depends on the output of the Wizard,
    '                but obviously it has not been called yet.
    myFtpWebRequest = CType(WebRequest.Create(ftpServer + ftpPath + NewFilename), FtpWebRequest)
    myFtpWebRequest.Method = WebRequestMethods.Ftp.UploadFile
    myFtpWebRequest.UseBinary = True

    Dim myFileStream As Stream = FileUpload1.FileContent
    myFtpWebRequest.ContentLength = myFileStream.Length

    'Function two?
    Dim requestStream As Stream = myFtpWebRequest.GetRequestStream()
    myFileStream.CopyTo(requestStream)
    requestStream.Close()

    myFtpWebResponse = CType(myFtpWebRequest.GetResponse(), FtpWebResponse)
    myFtpWebResponse.Close()
End Sub

— ANSWER —

Here’s my final implementation based on input from Icarus 🙂

For brevity I have excluded the error catching.

'This function is what kicks things off...
Protected Sub UploadFileToWebServer() Handles btnUploadFile.Click
    Dim TempDir As String = "C:\TEMP", FileName As String = "uploadedfile.tmp", FilePath As String
    If Not Directory.Exists(TempDir) Then
        Directory.CreateDirectory(TempDir).Attributes = FileAttributes.Directory
    End If
    FilePath = TempDir + "\" + FileName
    Session.Add("FileName", File1.FileName) 'Keep track of uploaded file name
    File1.SaveAs(FilePath)
    Session.Add("File", FilePath)
End Sub

After the file is uploaded to the web server, we can continue through the wizard, and when the “Finish” button is clicked, the wizard data gets submitted to the database. The filename is based on the inserted record ID. The following function gets called by the “Final” button click after the record is inserted, and the file finally gets uploaded to the FTP server with the filename changed accordingly.

Protected Sub UploadFileToFtpServer(ByVal FileLinkStr As String)
    Dim myFtpWebRequest As FtpWebRequest
    Dim myFtpWebResponse As FtpWebResponse

    'Defines the filename, path, and upload method, and connection credentials
    myFtpWebRequest = CType(WebRequest.Create(ftpServer + ftpPath + FileLinkStr), FtpWebRequest)
    'Be sure to authenticate prior to uploading or nothing will upload and no error
    myFtpWebRequest.Credentials = New NetworkCredential(ftpUsername, ftpPassword)
    myFtpWebRequest.Method = WebRequestMethods.Ftp.UploadFile
    myFtpWebRequest.UseBinary = True

    'Streams the file to the FTP server
    'Retrieves File temporarily uploaded to the Web Server during Wizard Processing
    Dim iStream As New FileInfo(Session.Item("File"))
    Dim myFileStream As Stream = iStream.OpenRead
    myFtpWebRequest.ContentLength = myFileStream.Length
    Dim requestStream As Stream = myFtpWebRequest.GetRequestStream()
    myFileStream.CopyTo(requestStream)
    requestStream.Close()

    myFtpWebResponse = CType(myFtpWebRequest.GetResponse(), FtpWebResponse)
    myFtpWebResponse.Close()
End Sub

Answer 1

Your understanding is correct. Once you upload the file to the web server (you’d need to place it in a temp directory somewhere and keep track of the file name you gave it) and the wizard completes successfully, you grab that file, rename it accordingly and upload it to the ftp server. If fails, simply call:

File.Delete(Path_to_file_uploaded_on_temp_directory);

You can keep track of the file name given originally, by storing it in Session, for example. When you upload the file to the server initially, do something like Session["FileName"]=Path_to_temp_directory+fileName;

On the final step of the Wizard, get the file name from Session and either rename it and upload it to the FTP Server or delete it.

Of course you need to account for possible name conflicts, etc. You can use a Guid to generate a random name for the file, for example.

I hope I explained this clearly.

EDIT

To make sure I understand correctly…

1. You need your user to go through all the steps of a Wizard kind of thing
2. During the process, you ask your user to upload a file.
3. Because the user has to select a file before the last step of the wizard, you are forced to upload the file immediately the user clicks on the “Next” button to go to the next step of the wizard.
4. At the very last step of the Wizard, you need to determine whether the file the user has selected should be uploaded to an ftp server (presumably, another box different from your web server) or should be discarded completely.
5. If the file needs to be uploaded to the FTP server, it needs to be renamed with a special name.

Based on the above, my suggestion is:

1. When the user clicks “Next” on the step where he selects the file from his computer, you need to save the file immediately to a temporary location on your web server. You save the file to this temporary folder on your web server by doing something like:

   if(FileUpload1.HasFile) //user selected a file
   {
       try
       {
         //D:\temp is a temp directory on the Web Server
         FileUpload1.PostedFile.SaveAs(@"D:\temp\"+FileUpload1.FileName);
         //Store the FULL PATH TO the file just uploaded on Session 
         Session["FileName"]="D:\temp\"+FileUpload1.FileName;
       }
       catch (Exception ex)
       {
          //Handle it.
       }
   }
   

2. On the last step of the wizard, assuming everything was successful, do this

    Dim myFtpWebRequest As FtpWebRequest
    Dim myFtpWebResponse As FtpWebResponse
    ' You know the NewFileName because it's the output of the wizard
   
    myFtpWebRequest = CType(WebRequest.Create(ftpServer + ftpPath + NewFilename),  FtpWebRequest)
    myFtpWebRequest.Method = WebRequestMethods.Ftp.UploadFile
    myFtpWebRequest.UseBinary = True
   
    'Here you need to read the Original File
    Dim myFileStream As Stream = new FileStream(Session["FileName"]),FileMode.Open,FileAccess.Read,FileShare.ReadWrite)
    myFtpWebRequest.ContentLength = myFileStream.Length
   
   
    Dim requestStream As Stream = myFtpWebRequest.GetRequestStream()
    myFileStream.CopyTo(requestStream)
    requestStream.Close()
   
    myFtpWebResponse = CType(myFtpWebRequest.GetResponse(), FtpWebResponse)
    myFtpWebResponse.Close()
   

3. If you decide that you should delete the original file uploaded by the user because he did not complete the wizard successfully, you can simply do:

    try
    {
       File.Delete (Session["FileName"]);
    }
    catch(Exception ex)
    {
       //Handle it.
    }