WebClient not posting data.

[Manuel]

I have an asp page ("test.asp") that presents the data it receives from a
post.When I try the following code, test.asp doesn't return the values
(supposedly) posted to it. If I make a web page with a form and the values,
test.asp reports them fine.

----------------------------

Dim thePost As String = "Variable1=Value1&Variable2=Value2&Variable3=Value3"
Dim thePage As Byte()
Dim MyWebClient As New System.Net.WebClient
thePage = MyWebClient.UploadData("http://localhost/test.asp",
System.Text.Encoding.ASCII.GetBytes(thePost))

----------------------------

Does anyone have an idea why the WebClient is not posting the data?


.... I made some progress, but encountered other problems

I made a successful post using the following code:

----------------------------
Dim oNameValues As New System.Collections.Specialized.NameValueCollection
oNameValues.Add("Variable1", "Value1")
oNameValues.Add("Variable2", "Value2")
oNameValues.Add("Variable3", "Value3")

Dim thePage As Byte()
Dim MyWebClient As New System.Net.WebClient
thePage = MyWebClient.UploadValues("http://localhost/test.asp", "POST",
oNameValues)
----------------------------

The problem is that I cannot change the Content-Type. If I try to change the
content type with:

MyWebClient.Headers.Add("Content-Type", "multipart/form-data")

I get the following error at the .UploadValues line:

----------------------------
An unhandled exception of type 'System.Net.WebException' occurred in
system.dll

Additional information: The Content-Type header cannot be changed from its
default value for this request.
----------------------------

How can I make a successful post using "Content-Type = multipart/form-data"?




PS. Sorry for the cross-post, I first submitted it to the adonet group by
mistake.

 

[Guest]

Hi Manuel,
Instead of uploading the form data to the server, form variable POST it can
be achieved by writing the data in the server (ur web app).

I have given the sample in C#, with the content type
"application/x-www-form-urlencoded".

For eg:- to POST the form variable "Variable1" with its value "Value1",

add a method to write the content to the URL,

private void postData(WebRequest webRequest, string data)
{
bytes = System.Text.Encoding.ASCII.GetBytes (data);
webRequest.ContentLength = bytes.Length;

Stream outputStream = webRequest.GetRequestStream();
outputStream.Write (bytes, 0, bytes.Length);
outputStream.Close ();
}

Call this method, after setting ur content type , i.e,

the actual code shld. be,


WebRequest objWebRequest = WebRequest.Create("http://urwebsite/abc.aspx");
objWebRequest.Method = "POST";
objWebRequest.ContentType = "application/x-www-form-urlencoded";

postData = "Variable1=Value1";

postData(objWebRequest,postData);

WebResponse objResponse = objWebRequest.GetResponse();

string strResponse = "";

using (StreamReader sr = new StreamReader(objResponse.GetResponseStream()) )
{
strResponse = sr.ReadToEnd();
sr.Close();
}

objResponse.Close();

Hope this helps u.......

Regards,
Kamal T.

 

[Manuel]

Thank you for your suggestion.

The problem is that I have to use the System.Net.WebClient object because I
need to maintain the web session (and cookies) when I "navigate" the site
after I log in.

Since the System.Net.WebClient doesn't have a WebRequest property, I don't
know how to "link" your example with the WebClient object.
Is this possible?

 

[Joerg Jooss]

I have an asp page ("test.asp") that presents the data it receives
from a post.When I try the following code, test.asp doesn't return
the values (supposedly) posted to it. If I make a web page with a
form and the values, test.asp reports them fine. [...]

The problem is that I cannot change the Content-Type. If I try to
change the content type with:

MyWebClient.Headers.Add("Content-Type", "multipart/form-data")

I get the following error at the .UploadValues line:

----------------------------
An unhandled exception of type 'System.Net.WebException' occurred in
system.dll

Additional information: The Content-Type header cannot be changed
from its default value for this request.

WebClient uses multipart/form-data only for file uploads. Unfortunately,
there's no direct support for multipart/form-data in the FCL other than that
special case. You'll have to implement one yourself using HttpWebRequest if
you want to use multipart/form-data for another purpose.

Cheers,