Uploading Image MultiPart Form HTTPWebRequest - Getting Image Data To String?

Question

I am trying to upload a multi-part form with HTTPWebRequest & all is ok until I added an image to upload, mainly I am trying to do exactly the same request as a browser makes which looks like this:

-----------------------------41184676334
Content-Disposition: form-data; name="file"; filename="guitar tape.jpg"
Content-Type: image/jpeg

IMAGEDATAHERE
-----------------------------41184676334
Content-Disposition: form-data; name="save"

save
-----------------------------41184676334--

I am lost on how to format / read the image to set it into the request that I am making below:

            Dim boundary As String = "-----------------------------" & DateTime.Now.Ticks.ToString("x")
        Dim req As HttpWebRequest = DirectCast(WebRequest.Create("http://www.mysite.com/upload.php"), HttpWebRequest)
        req.Method = "POST"
        req.ContentType = "multipart/form-data; boundary=" & "---------------------------" & DateTime.Now.Ticks.ToString("x")
        req.KeepAlive = False
        Dim builder As New StringBuilder()
        builder.Append(boundary & vbCrLf & "Content-Disposition: form-data; name=""variable1""" & vbCrLf & vbCrLf & "1" & vbCrLf)
        builder.Append(boundary & vbCrLf & "Content-Disposition: form-data; name=""file""; filename=""" & FileName & """" & vbCrLf)
        builder.Append("Content-Type: application/octet-stream")
        builder.Append(vbCrLf & vbCrLf)
        ' Add Photo Here
        If UpdateImage = True Then
            ' Load Image
            Dim ImageData As System.Drawing.Image
            Dim fs As New System.IO.FileStream(ImagePath, System.IO.FileMode.Open)
            ImageData = Image.FromStream(fs)
            fs.Close()
            ' Add Image To Header
            builder.Append(ImageData)
            builder.Append(vbCrLf)
        Else
            builder.Append(vbCrLf)
        End If
        builder.Append(boundary & vbCrLf & "Content-Disposition: form-data; name=""save""" & vbCrLf & vbCrLf & "save")
        ' Footer Bytes
        Dim close As Byte() = Encoding.UTF8.GetBytes("--")
        Dim postHeader As String = builder.ToString()
        Dim postHeaderBytes As Byte() = Encoding.UTF8.GetBytes(postHeader)
        Dim boundaryBytes As Byte() = Encoding.ASCII.GetBytes(vbCrLf & boundary & "--" & vbCrLf)
        Dim length As Long = postHeaderBytes.Length + boundaryBytes.Length
        req.ContentLength = length
        Dim requestStream As Stream = req.GetRequestStream()
        Dim fulllength As Integer = postHeaderBytes.Length + boundaryBytes.Length
        ' Write out our post header
        requestStream.Write(postHeaderBytes, 0, postHeaderBytes.Length)
        ' Write out the trailing boundary
        requestStream.Write(boundaryBytes, 0, boundaryBytes.Length)
        Dim responce As WebResponse
        responce = req.GetResponse()
        requestStream.Close()
        Dim s As Stream = responce.GetResponseStream()
        Dim sr As New StreamReader(s)
        Dim Content As String = sr.ReadToEnd()

At the moment it is simply posting "System.Drawing.Bitmap" as the image data but I am not sure how to get the same raw data for the image that looks like this:

    J©õݨe‚Lnž¿Ëã/ǧúÐ5ý¼C÷Cý>ß’t;fm—=Äw:�/E±ËÙÏ$á@%Pc>×    Šgw.²Ab“:ÅÓù:ϯÌh6à€Z§Ó‚g£®hÚD6¨Ø^Ú2ô`ä¨L�YÆÄÅCX#I“ÈÌãj¦L˜•’|¥�Eb¡ëQ–¤Ú, 3\UzL  öÔoj4�•±’u«c¼#„oÕ`îF>·o—ŠûÅ«ÎÑ™¶Ç˜ýº*i°œÈVŒ�Qû”Ñ[.�ÔmçE•ì¦eNCh�Ù
é§�É$m¿ôš"»ÌNæ(VÌmp›F¹XÈ88™ªüµ…d•XµÔÜ#�ˆŠv‘º‚F‚§Yûb

Any ideas on how I could do this or would I need to change my methods?

Answer 1

    builder.Append(ImageData)

is not correct. you need read the image as byte, then add the byte[] to the multipart post.

see details at Using HttpWebRequest to POST data/upload image using multipart/form-data

and make sure use a http sniffer (i.e. fiddler) to see what it is actually sending.

first, load image into byte array, then convert it to base64:

imgBase64 = Convert.ToBase64String(my_image_byte_array)