Question

I have to pass parameters to a WebRequest. The parameters are available as a NameValueCollection. I have to return a byte array.

How do I do that?

Answer 1

I’m assuming you mean HttpWebRequest, since WebRequest is just an abstract class. And, I’m assuming you’re doing a POST, since with a GET you can just slap it onto the end of the URL.

So, you need to first create the body of the POST, which is written into the web requests’s request stream:

var sb = new StringBuilder();
foreach(var item in myCollection) {
  sb.AppendFormat("{0}={1}&", item.Name, HttpUtility.UrlEncode(item.Value.ToString()));
}
sb.Remove(sb.Length - 1, 1); // remove the last '&'

At this point, you’ll have a string buffer that contains a string like "myVal1=Hello%20World&myVal2=5". Now you want to write it to the request’s stream:

var request = (HttpWebRequest)HttpWebRequest.Create("http://somewhere.url/asdf/asdf");
request.Method = "POST";
var stream = request.GetRequestStream();
var bytes = Encoding.UTF8.GetBytes(sb.ToString());
request.ContentType="application/x-www-form-urlencoded;charset=UTF-8";
request.ContentLength = data.Length;
stream.Write(bytes, 0, bytes.Length);
stream.Close();
var response = (HttpWebResponse)request.GetResponse();
// ... process the response ...

Hope this helps. I assumed your NameValueCollection was in the form of string -> object. Adjust the “item.Value” part if it differs. I also didn’t URL Encode the key of a pair, since i don’t think they accept url-encoded keys.

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• Sending Data with WebRequest – MSDN
• POST with C#