How to Add Parameters into a Webrequest

How to add parameters into a WebRequest?

If these are the parameters of url-string then you need to add them through '?' and '&' chars, for example http://example.com/index.aspx?username=Api_user&password=Api_password.

If these are the parameters of POST request, then you need to create POST data and write it to request stream. Here is sample method:

private static string doRequestWithBytesPostData(string requestUri, string method, byte[] postData,
                                        CookieContainer cookieContainer,
                                        string userAgent, string acceptHeaderString,
                                        string referer,
                                        string contentType, out string responseUri)
        {
            var result = "";
            if (!string.IsNullOrEmpty(requestUri))
            {
                var request = WebRequest.Create(requestUri) as HttpWebRequest;
                if (request != null)
                {
                    request.KeepAlive = true;
                    var cachePolicy = new RequestCachePolicy(RequestCacheLevel.BypassCache);
                    request.CachePolicy = cachePolicy;
                    request.Expect = null;
                    if (!string.IsNullOrEmpty(method))
                        request.Method = method;
                    if (!string.IsNullOrEmpty(acceptHeaderString))
                        request.Accept = acceptHeaderString;
                    if (!string.IsNullOrEmpty(referer))
                        request.Referer = referer;
                    if (!string.IsNullOrEmpty(contentType))
                        request.ContentType = contentType;
                    if (!string.IsNullOrEmpty(userAgent))
                        request.UserAgent = userAgent;
                    if (cookieContainer != null)
                        request.CookieContainer = cookieContainer;

                    request.Timeout = Constants.RequestTimeOut;

                    if (request.Method == "POST")
                    {
                        if (postData != null)
                        {
                            request.ContentLength = postData.Length;
                            using (var dataStream = request.GetRequestStream())
                            {
                                dataStream.Write(postData, 0, postData.Length);
                            }
                        }
                    }

                    using (var httpWebResponse = request.GetResponse() as HttpWebResponse)
                    {
                        if (httpWebResponse != null)
                        {
                            responseUri = httpWebResponse.ResponseUri.AbsoluteUri;
                            cookieContainer.Add(httpWebResponse.Cookies);
                            using (var streamReader = new StreamReader(httpWebResponse.GetResponseStream()))
                            {
                                result = streamReader.ReadToEnd();
                            }
                            return result;
                        }
                    }
                }
            }
            responseUri = null;
            return null;
        }

Adding parameters to an HttpWebRequest

HttpWebRequest request = WebRequest.CreateHttp("" + url);
//we could move the content-type into a function argument too.
request.ContentType = "application/x-www-form-urlencoded";
request.Method = "POST";
postParams.Add("oauth_token", ""); // where do I add this to the request??
try
{
    //this is how you do it
    using(var stream = await request.GetRequestStreamAsync())
    {
        byte[] jsonAsBytes = Encoding.UTF8.GetBytes(string.Join("&", postParams.Select(pp => pp.Key + "=" + pp.Value)));
        await stream.WriteAsync(jsonAsBytes, 0, jsonAsBytes.Length);
    }
    HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync();

    Debug.WriteLine(response.ContentType);
    System.IO.Stream responseStream = response.GetResponseStream();
    string data;
    using (var reader = new System.IO.StreamReader(responseStream))
    {
        data = reader.ReadToEnd();
    }
    responseStream.Close();

    return data;
}

Async Await HttpWebRequest Extensions:

public static class HttpExtensions
{
    public static Task<Stream> GetRequestStreamAsync(this HttpWebRequest request)
    {
        var tcs = new TaskCompletionSource<Stream>();

        try
        {
            request.BeginGetRequestStream(iar =>
           {
               try
               {
                   var response = request.EndGetRequestStream(iar);
                   tcs.SetResult(response);
               }
               catch (Exception exc)
               {
                   tcs.SetException(exc);
               }
           }, null);
        }
        catch (Exception exc)
        {
            tcs.SetException(exc);
        }

        return tcs.Task;
    }
    public static Task<HttpWebResponse> GetResponseAsync(this HttpWebRequest request)
    {
        var taskComplete = new TaskCompletionSource<HttpWebResponse>();
        request.BeginGetResponse(asyncResponse =>
        {
            try
            {
                HttpWebRequest responseRequest = (HttpWebRequest)asyncResponse.AsyncState;
                HttpWebResponse someResponse =
                   (HttpWebResponse)responseRequest.EndGetResponse(asyncResponse);
                taskComplete.TrySetResult(someResponse);
            }
            catch (WebException webExc)
            {
                HttpWebResponse failedResponse = (HttpWebResponse)webExc.Response;
                taskComplete.TrySetResult(failedResponse);
            }
        }, request);
        return taskComplete.Task;
    }
}

With the extensions, I think it's a little cleaner.

How to pass POST parameters to ASP.Net web request?

Try like this...

  string email = "YOUR EMAIL";
  string password = "YOUR PASSWORD";

  string URLAuth = "https://accounts.craigslist.org/login";
  string postString = string.Format("inputEmailHandle={0}&name={1}&inputPassword={2}", email, password);

  const string contentType = "application/x-www-form-urlencoded";
  System.Net.ServicePointManager.Expect100Continue = false;

  CookieContainer cookies = new CookieContainer();
  HttpWebRequest webRequest = WebRequest.Create(URLAuth) as HttpWebRequest;
  webRequest.Method = "POST";
  webRequest.ContentType = contentType;
  webRequest.CookieContainer = cookies;
  webRequest.ContentLength = postString.Length;
  webRequest.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1";
  webRequest.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
  webRequest.Referer = "https://accounts.craigslist.org";

  StreamWriter requestWriter = new StreamWriter(webRequest.GetRequestStream());
  requestWriter.Write(postString);
  requestWriter.Close();

  StreamReader responseReader = new StreamReader(webRequest.GetResponse().GetResponseStream());
  string responseData = responseReader.ReadToEnd();

  responseReader.Close();
  webRequest.GetResponse().Close();

HttpWebRequest GET with object as parameter

API Side:

You need to use [FromUri] attribute in your API action.

For more information about parameter binding please review this link.

public class SomeData
{
    public int Start { get; set; } 
    public int End { get; set; }
}
public SomeController : ApiController
{
    public HttpResponseMessage Get([FromUri] SomeData data) { ... }
}

Client Side

You need send your parameters in query as usual.

http://localhost/api/Some?Start=0&End=10

Also one more interesting link for details is here.

How to add query string to httpwebrequest

The best way to add a query string is as follows:

var targetUri = new Uri("http://www.example.org?queryString=a&b=c");
var webRequest = (HttpWebRequest)WebRequest.Create(targetUri);

var webRequestResponse = webRequest.GetResponse();

Remember: If you're using user input to construct the Uri, ensure that you validate it, escape it and don't trust it.

WebRequest POST with both file and parameters

The problem is that you're missing a '\n'. The following line:

string postData = "--" + boundary + "\nContent-Disposition: form-data\n";

should be:

string postData = "--" + boundary + "\nContent-Disposition: form-data\n\n";

And this line:

postData += "\n--" + boundary + "\nContent-Disposition: form-data; name=\"file\" filename=\"upload.pdf\" Content-Type: application/pdf\n\n"

is missing a '\n' before 'Content-Type'. It should be:

postData += "\n--" + boundary + "\nContent-Disposition: form-data; name=\"file\" filename=\"upload.pdf\"\nContent-Type: application/pdf\n\n"

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