Wenn (fileUpload.HasFile) = false

Question

hallo alle hier der Code dann werde ich meine Frage erklären: -

Protected Sub btnupload_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnUpload.Click 
    If (IsPostBack) Then 
     HandleUploadedFile() 
     Dim savePath As String = "Images\" 
     If (fileUpload.HasFile) Then 
      Dim fileName As String = fileUpload.FileName 
      savePath = Server.MapPath(savePath) + fileName 
      fileUpload.SaveAs(savePath) 
      Me.Label1.Text = "Your file was saved as " & fileName 
      adp.Insert(fileUpload.FileName) 
     Else 
      Me.Label1.Text = "You did not specify a file to upload." 
     End If 
    End If 
End Sub 

jedes Mal, wenn ich den Code zu verfolgen, sagt es, dass (fileUpload.HasFile)=false und nie den Code danach sieht, dann springt auf die sonst statment und das ist der Rest des Codes

Private Sub HandleUploadedFile() 
    ' get the root of the web site 
    Dim root As String = Server.MapPath("~/") 

    ' clean up the path 
    If Not root.EndsWith("\") Then 
     root += "\" 
    End If 

    ' make a folder to store the images in 
    Dim fileDirectory As String = root & "Images/" 

    ' create the folder if it does not exist 
    If Not System.IO.Directory.Exists(fileDirectory) Then 
     System.IO.Directory.CreateDirectory(fileDirectory) 
    End If 

    ' make a link to the new file 
    Dim link As String = "<a href='Images/{0}' target='_blank'>{1}</a>{2}{3}" 

    ' loop through the file in the request 
    For i As Integer = 0 To Request.Files.Count - 1 

     ' get the file instance 
     Dim fi As HttpPostedFile = Request.Files.[Get](i) 

     ' create a byte array to store the file bytes 
     Dim fileBytes As Byte() = New Byte(fi.ContentLength - 1) {} 

     ' fill the byte array 
     Using stream As System.IO.Stream = fi.InputStream 
      stream.Read(fileBytes, 0, fi.ContentLength) 
     End Using 

     ' create a random file name 
     Dim fileName As String = Guid.NewGuid().ToString() 

     'write the original file to the file system 
     File.WriteAllBytes(fileDirectory + fileName & ".jpg", fileBytes) 
     litText.Text += String.Format(link, fileName & ".jpg", fileName & " Original", "<br/>", "") 

     ' write the resized file to the file system 
     File.WriteAllBytes(fileDirectory + fileName & "_small.jpg", ResizeImageFile(fileBytes, 100)) 
     litText.Text += String.Format(link, fileName & "_small.jpg", fileName & " Small", "<br/>", "<br/>") 

     ' cleanup 
     litText.Visible = True 
     fileBytes = Nothing 
    Next 
End Sub 
Private Shared Function ResizeImageFile(ByVal imageFile As Byte(), ByVal targetSize As Integer) As Byte() 
    Using oldImage As System.Drawing.Image = System.Drawing.Image.FromStream(New MemoryStream(imageFile)) 
     Dim newSize As Size = CalculateDimensions(oldImage.Size, targetSize) 
     Using newImage As New Bitmap(newSize.Width, newSize.Height, PixelFormat.Format24bppRgb) 
      Using canvas As Graphics = Graphics.FromImage(newImage) 
       canvas.SmoothingMode = SmoothingMode.AntiAlias 
       canvas.InterpolationMode = InterpolationMode.HighQualityBicubic 
       canvas.PixelOffsetMode = PixelOffsetMode.HighQuality 
       canvas.DrawImage(oldImage, New Rectangle(New Point(0, 0), newSize)) 
       Dim m As New MemoryStream() 
       newImage.Save(m, ImageFormat.Jpeg) 
       Return m.GetBuffer() 
      End Using 
     End Using 
    End Using 
End Function 
Private Shared Function CalculateDimensions(ByVal oldSize As Size, ByVal targetSize As Integer) As Size 
    Dim newSize As New Size() 
    If oldSize.Height > oldSize.Width Then 
     newSize.Width = CInt((oldSize.Width * (CSng(targetSize)/CSng(oldSize.Height)))) 
     newSize.Height = targetSize 
    Else 
     newSize.Width = targetSize 
     newSize.Height = CInt((oldSize.Height * (CSng(targetSize)/CSng(oldSize.Width)))) 
    End If 
    Return newSize 
End Function 

End Class 

Answer 1

ich denke, es könnte sein, dass Sie Sie in das Verzeichnis-Datei schreiben und dabei, dass es die Form Fileupload löscht. Dies geschieht, bevor Sie Ihre if-Anweisung ausführen. Versuchen Sie, Ihre if/else über die Funktion "handleuploadedfile()" zu bewegen. Dies sollte sicherstellen, dass Sie das Upload-Formular überprüfen können, bevor das System die Datei schreibt und aus dem Upload-Formular entfernt.

Answer 2

Der Grund, warum fileUpload.HasFiles = False ist, dass zu dem Zeitpunkt, dass der Code erreicht ist, der Dateistream innerhalb der HandleUploadFile Subroutine geschlossen wurde.

‚diese Anweisung using schließt den ursprünglichen Eingangsstrom und dort entfernt es ‘ aus dem Fileupload

Using stream As System.IO.Stream = fi.InputStream    
stream.Read(fileBytes, 0, fi.ContentLength)   
End Using 

Answer 3

Überprüfen Sie, ob you'r eine Update verwenden, wenn ja, dann in Page.Init so etwas tun:

protected void userView_Init(object sender, EventArgs e) 
{ 
ScriptManager.GetCurrent(this).RegisterPostBackControl(uploadFileButton); 
}