Upload files asynchronously with ASP.NET - asp.net

Question

I'm trying to make an asynchronous upload operation but I got this error message:
Error occurred, info=An exception
occurred during a WebClient request`.
Here's the upload function:
Private Sub UploadFile()
Dim uploads As HttpFileCollection
uploads = HttpContext.Current.Request.Files
Dim uri As Uri = New Uri("C:\UploadedUserFiles\")
Dim client = New WebClient
AddHandler client.UploadFileCompleted, AddressOf UploadFile_OnCompleted
For i As Integer = 0 To (uploads.Count - 1)
If (uploads(i).ContentLength > 0) Then
Dim c As String = System.IO.Path.GetFileName(uploads(i).FileName)
Try
client.UploadFileAsync(uri, c)
Catch Exp As Exception
End Try
End If
Next i
End Sub
Public Sub UploadFile_OnCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.AsyncCompletedEventArgs)
Dim client As WebClient = CType(e.UserState, WebClient)
If (e.Cancelled) Then
labMessage.Text = "upload files was cancelled"
End If
If Not (e.Error Is Nothing) Then
labMessage.Text = "Error occured, info=" + e.Error.Message
Else
labMessage.Text = "File uploaded successfully"
End If
End Sub
Update 1:
Private Sub UploadFile()
Dim uploads As HttpFileCollection
Dim fileToUpload = "C:\Demo\dummy.doc"
Dim uri As Uri = New Uri("C:\UploadedUserFiles\")
Dim client = New WebClient
AddHandler client.UploadFileCompleted, AddressOf UploadFile_OnCompleted
client.UploadFileAsync(uri, fileToUpload)
End Sub
client.UploadFileAsync(uri, fileToUpload) is throwing this error message
Error occured, info=System.Net.WebException: The request was aborted: The request was canceled. at System.Net.FileWebRequest.EndGetResponse(IAsyncResult asyncResult) at System.Net.WebClient.GetWebResponse(WebRequest request, IAsyncResult result) at System.Net.WebClient.DownloadBitsResponseCallback(IAsyncResult result)

Answer 1

By calling GetFileName you're truncating whatever path information was there. You should provide UploadFileAsync with a full path name.
Also, replace e.Error.Message with just e.Error so you get the full error details including inner exceptions. This will provide more info and probably lead you to the answer.

Answer 2

Dim uri As Uri = New Uri("C:\UploadedUserFiles\")
The above statement is wrong, how come you have Uri as a file system path, it should be "http://" or "https://" , if you are trying to upload it to your local asp.net web site project then you must have a url something like http://localhost:PORT/UploadedUserFiles ... and you will know port number when you execute project.
Dim uri As Uri = New Uri("http://localhost:PORT/Upload.aspx")

Answer 3

Try this:
1) Create a new class MyWebClient.
Class MyWebClient
Inherits WebClient
Protected Overrides Function GetWebRequest(address As Uri) As WebRequest
Dim req = MyBase.GetWebRequest(address)
Dim httpReq = TryCast(req, HttpWebRequest)
If httpReq IsNot Nothing Then
httpReq.KeepAlive = False
End If
Return req
End Function
End Class
2) Use this class instead of the default WebRequest.
Private Sub UploadFile()
Dim uploads As HttpFileCollection
uploads = HttpContext.Current.Request.Files
Dim uri As Uri = New Uri("C:\UploadedUserFiles\")
Dim client = New MyWebClient
AddHandler ...
I hope this helps.

Answer 4

From the reference to HttpContext.Current.Request.Files I am assuming that your are running the code in a web project. You don't have to use WebClient to save the file to your disk. All you have to do is this:
Private Sub UploadFile()
Dim uploads As HttpFileCollection
uploads = HttpContext.Current.Request.Files
Dim path As String = "C:\UploadedUserFiles\"
For i As Integer = 0 To (uploads.Count - 1)
If (uploads(i).ContentLength > 0) Then
Dim p As String = System.IO.Path.Combine(path, System.IO.Path.GetFileName(uploads(i).FileName))
uploads(i).SaveAs(p)
End If
Next i
End Sub
I'm not that good with VB.. so there might be syntax problems :) bear with me..

Answer 5

You can't upload files from the ASP.NET web request asyncronously via this mechanism. The file is actually in the body of the http request so it is already on the server. Request.Files provides a stream to the files that are already on the server.
You could use something like Silverlight or Flash from the client side.

Answer 6

You might want to investigate the AJAX Control Toolkit and use the AsyncFileUpload control.
The control has a server side event when upload is complete. (UploadedComplete)
It also has a SaveAs(string filename) method for the uploaded file.
Simple Usage:
Markup
<asp:AsyncFileUpload ID="upload" runat="server" OnUploadedComplete="displayFile"/>
Code Behind
protected void displayFile(object sender, AjaxControlToolkit.AsyncFileUploadEventArgs e)
{
upload.SaveAs("C:\\text.txt");//server needs permission
}

Answer 7

Try to add Header information to the WebClient Object as below :
With webClient
.Headers.Add("Content-Type", Web.MimeMapping.GetMimeMapping("C:\filename.txt"))
.Headers.Add("Keep-Alive", "true")
.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)")
.Credentials = New Net.NetworkCredential("UserName", "password")
End With