Receiving POST data in ASP.NET

Posted by grast on Stack Overflow See other posts from Stack Overflow or by grast
Published on 2010-04-29T19:18:28Z Indexed on 2010/05/01 12:17 UTC
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Hi, I want to use ASP for code generation in a C# desktop application.

To achieve this, I set up a simple host (derived from System.MarshalByRefObject) that processes a System.Web.Hosting.SimpleWorkerRequest via HttpRuntime.ProcessRequest. This processes the ASPX script specified by the incoming request (using System.Net.HttpListener to wait for requests).

The client-part is represented by a System.ComponentModel.BackgroundWorker that builds the System.Net.HttpWebRequest and receives the response from the server.

A simplified version of my client-part-code looks like this:

private void SendRequest(object sender, DoWorkEventArgs e)
{
    // create request with GET parameter
    var uri = "http://localhost:9876/test.aspx?getTest=321";
    var request = (HttpWebRequest)WebRequest.Create(uri);

    // append POST parameter
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";

    var postData = Encoding.Default.GetBytes("postTest=654");
    var postDataStream = request.GetRequestStream();
    postDataStream.Write(postData, 0, postData.Length);

    // send request, wait for response and store/print content
    using (var response = (HttpWebResponse)request.GetResponse())
    {
        using (var reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
        {
            _processsedContent = reader.ReadToEnd();
            Debug.Print(_processsedContent);
        }
    }
}

My server-part-code looks like this (without exception-handling etc.):

public void ProcessRequests()
{
    // HttpListener at http://localhost:9876/
    var listener = SetupListener();

    // SimpleHost created by ApplicationHost.CreateApplicationHost
    var host = SetupHost();

    while (_running)
    {
        var context = listener.GetContext();

        using (var writer = new StreamWriter(context.Response.OutputStream))
        {
            // process ASP script and send response back to client
            host.ProcessRequest(GetPage(context), GetQuery(context), writer);
        }

        context.Response.Close();
    }
}

So far all this works fine as long as I just use GET parameters. But when it comes to receiving POST data in my ASPX script I run into trouble. For testing I use the following script:

// GET parameters are working:
var getTest = Request.QueryString["getTest"];
Response.Write("getTest: " + getTest);           // prints "getTest: 321"

// don't know how to access POST parameters:
var postTest1 = Request.Form["postTest"];        // Request.Form is empty?!
Response.Write("postTest1: " + postTest1);       // so this prints "postTest1: "

var postTest2 = Request.Params["postTest"];      // Request.Params is empty?!
Response.Write("postTest2: " + postTest2);       // so this prints "postTest2: "

It seems that the System.Web.HttpRequest object I'm dealing with in ASP does not contain any information about my POST parameter "postTest". I inspected it in debug mode and none of the members did contain neither the parameter-name "postTest" nor the parameter-value "654". I also tried the BinaryRead method of Request, but unfortunately it is empty. This corresponds to Request.InputStream==null and Request.ContentLength==0. And to make things really confusing the Request.HttpMethod member is set to "GET"?!

To isolate the problem I tested the code by using a PHP script instead of the ASPX script. This is very simple:

print_r($_GET);  // prints all GET variables
print_r($_POST); // prints all POST variables

And the result is:

Array
(
    [getTest] => 321
)
Array
(
    [postTest] => 654
)

So with the PHP script it works, I can access the POST data. Why does the ASPX script don't? What am I doing wrong? Is there a special accessor or method in the Response object?

Can anyone give a hint or even know how to solve this? Thanks in advance.

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