Uploading a binary file as part of a POST WebRequest

[Anthony Papillion]

Hello Everyone,

I've been searching this out for almost three weeks and I simply can't find
an answer anywhere. I see a lot of people asking about it but nobody seems
to know the answer. Since I've gotten a few questions answered on this
group before, I'm going to ask the question again here. It's about uploading
a file as part of a WebRequest.

My application is a mobile one which means I'm using the .NET Compact
Framework and thus, don't have access to the WebClient.UploadFile method.
But even if I did, that wouldn't work here since I need to pass several
parameters along and UploadFile() doesn't allow you to do that anyway.

The documentation to the API I'm working with tells me to create a POST
request and pass the following data to the API:

Subject - which is the subject of the file being uploaded
Recipient - the person receiving notification
Source - The raw binary data of the file to send

Obviously, since the API calls for this, this can be done, but HOW do I do
it? Note that I need to be able to do this without any third party
assemblies. It has to be a standard POST using WebRequest.

Can anyone give me some direction?

Thanks!
Anthony

 

[Michel Posseth [MCP]]

Hello Anthony


probably the API works with multipart form data


I have once written an example here in this group for someone who needed
this for the twitpic API
dig dig dig dig ,,,,,,,,


And here it is , the code sends a picture and some text to a twitter
account with the webrequest as you see you can send parameters as form data
see if you can convert it to your needs or maybe it gives you some ideas on
how to do what you want .


<<<<
'Michel Posseth [MCP]
'Created : 23-02-2009
'(e-mail address removed)
Imports System
Imports System.IO
Imports System.Net
Imports System.Xml
Imports System.Web
Imports System.Collections.Generic
Imports System.Text
Namespace VBDC
Public Class ClsTwitPic
Public Function SendPicToTwitPic(ByVal userName As String, ByVal
password As String, ByVal Message As String, ByVal ImgPath As String) As
String
Using fs As System.IO.FileStream = New FileStream(ImgPath,
FileMode.Open, FileAccess.Read)
Dim ImgData As Byte() = New Byte(fs.Length - 1) {}
fs.Read(ImgData, 0, ImgData.Length)
Return SendPicToTwitPic(userName, password, ImgData,
Message)
End Using
End Function
Private Function SendPicToTwitPic(ByVal UserName As String, ByVal
PassWord As String, ByVal Image As Byte(), Optional ByVal Message As String
= "", Optional ByVal Uri As String = "http://twitpic.com/api/uploadAndPost")
As String
Dim ret As String = String.Empty
Dim request As HttpWebRequest =
DirectCast(WebRequest.Create(Uri), HttpWebRequest)
request.Method = "POST"
request.Timeout = 30000


If Not String.IsNullOrEmpty(UserName) AndAlso Not
String.IsNullOrEmpty(PassWord) Then


Dim boundary As String = System.Guid.NewGuid().ToString()


request.Credentials = New NetworkCredential(UserName,
PassWord)


request.Headers.Add("Accept-Language",
request.PreAuthenticate = True
request.ContentType =
String.Format("multipart/form-data;boundary={0}", boundary)


Dim header As String = String.Format("--{0}", boundary)
Dim footer As String = header & "--"


Dim contents As New StringBuilder()


contents.Append(header)
contents.Append(vbCrLf)
contents.Append("Content-Disposition:
form-data;name=""username""" & vbCrLf)
contents.Append(vbCrLf)
contents.Append(UserName)
contents.Append(vbCrLf)


contents.Append(header)
contents.Append(vbCrLf)
contents.Append("Content-Disposition:
form-data;name=""password""" & vbCrLf)
contents.Append(vbCrLf)
contents.Append(PassWord)
contents.Append(vbCrLf)


If Not String.IsNullOrEmpty(Message) Then
contents.Append(header)
contents.Append(vbCrLf)
contents.Append("Content-Disposition:
form-data;name=""message""" & vbCrLf)
contents.Append(vbCrLf)
contents.Append(Message)
contents.Append(vbCrLf)
End If


contents.Append(header)
contents.Append(vbCrLf)
contents.Append("Content-Disposition:form-data;
name=""media"";filename=""image.jpg""" & vbCrLf)
contents.Append("Content-Type: image/jpeg" & vbCrLf)
contents.Append(vbCrLf)


Dim Einde As String = vbCrLf & header & vbCrLf
Dim BodyBytes As Byte() =
Encoding.UTF8.GetBytes(contents.ToString())
Dim footerBytes As Byte() = Encoding.UTF8.GetBytes(Einde)


request.ContentLength = BodyBytes.Length + Image.Length +
footerBytes.Length


Using requestStream As Stream = request.GetRequestStream()
requestStream.Write(BodyBytes, 0, BodyBytes.Length)
requestStream.Write(Image, 0, Image.Length)
requestStream.Write(footerBytes, 0, footerBytes.Length)
requestStream.Flush()
requestStream.Close()
Using response As WebResponse = request.GetResponse()
Using reader As New
StreamReader(response.GetResponseStream())
ret = reader.ReadToEnd()
End Using
End Using
End Using
End If


Return ret
End Function


End Class


End Namespace




Usage


Public Class Form1


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click


Dim TwitPic As New VBDC.ClsTwitPic


Debug.WriteLine(TwitPic.SendPicToTwitPic("YourUsername",


End Sub


End Class


the response i got was OK




when viewing my twitter account ( michel1973 ) i found my send picture
and the text i entered so it works


Regards


Michel Posseth [MCP] , VBDC
http://www.vbdotnetcoder.com/

HTH



Michel Posseth

 

[Anthony Papillion]

Hello,

Then you could use HttpWebRequest (which seems to be available in the
Compact Framework) and handle the request detail yourself.

See :
http://stackoverflow.com/questions/566462/upload-files-with-httpwebrequest-multipart-form-data
or
http://aspnetupload.com/Upload-File-POST-HttpWebRequest-WebClient-RFC-1867.aspx

(C# but should translate easily to VB).

Also you could create an APSX page that would accept something similar to
the API you are targetting allowing :
- to see what is the correct format by looking at what is sent when you
post from the browser (using either the Fiddler tool client side or
Request.SaveAs server side)
- and from there to test that your code ultimately creates a request that
is similar to the one you got above using your browser

As usual, thank you for your help! Checking out the links now

Anthony

 

[Anthony Papillion]

Hello Anthony


probably the API works with multipart form data


I have once written an example here in this group for someone who needed
this for the twitpic API
dig dig dig dig ,,,,,,,,


And here it is , the code sends a picture and some text to a twitter
account with the webrequest as you see you can send parameters as form
data
see if you can convert it to your needs or maybe it gives you some ideas
on how to do what you want .

Thank you sir! Exactly what I'm looking for. You just saved me a bunch of
work and puzzlement!

Anthony