C# WebRequest GET/POST

Question

So I thought it's time for me to learn C#, be easy with me guys, I'm very new to this.

I'm trying to create a very simple application (I'm using Windows Forms Application). My goal is:

1. Using "GET" method, get the web page
2. Read a text field (this value changes every time that the user is accessing the page
3. Using "POST" method, send some values accordingly

Here is my code so far:

  private void button2_Click(object sender, EventArgs e)
{
    string URI = "http://localhost/post.php";
    string myParameters = "field=value1&field2=value2";

    using (WebClient wc = new WebClient())
    {
        string getpage = wc.DownloadString("http://localhost/post.php");
        MessageBox.Show(getpage);
        wc.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
        string HtmlResult = wc.UploadString(URI, myParameters);
        MessageBox.Show(HtmlResult);
    }
}

So far so good, It's working but it's not entirely what I want to achieve here. I'm able to use POST method, but how do I use GET before sending the data? I want to send data according to GET result.

Please let me know if I should be giving a better description to what I'm trying to do.

Thanks.

Edit
This is my PHP Code:

<?php

    $a = session_id();

    if(empty($a))
        session_start();

        echo "Session: ".session_id()."<br/>\n";

Now, back to my C# code, I get different session ID in the two messages

Answer 1

Reading data with GET

Please refer to this answer: Easiest way to read from a URL into a string in .NET

using(WebClient client = new WebClient()) {
    string s = client.DownloadString(url);
}

Sessions

By default WebClient does not use any Session. So every call is handled as if you created a new Session. To do that you need something like this:

Please refer to these answers:

1. Using CookieContainer with WebClient class

2. Reading Response From URL using HTTP WEB REQUEST

Example code

public class CookieAwareWebClient : WebClient
{
    private readonly CookieContainer m_container = new CookieContainer();

    protected override WebRequest GetWebRequest(Uri address)
    {
        WebRequest request = base.GetWebRequest(address);
        HttpWebRequest webRequest = request as HttpWebRequest;
        if (webRequest != null)
        {
            webRequest.CookieContainer = m_container;
        }
        return request;
    }
}

// ...

private void button2_Click(object sender, EventArgs e)
{
    string URI = "http://localhost/post.php";
    string myParameters = "field=value1&field2=value2";

    using (WebClient wc = new CookieAwareWebClient())
    {
        string getpage = wc.DownloadString("http://localhost/post.php");
        MessageBox.Show(getpage);
        wc.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
        string HtmlResult = wc.UploadString(URI, myParameters);
        MessageBox.Show(HtmlResult);
    }
}

Answer 2

The GET method is really nothing but the parameters passed through the address line, just send your request to string.Format("{0}?{1}", URI, myParameters) (or URI + "?" + myParameters) and simply read response.

Answer 3

I know its an long time ago but :

       byte[] readedData = null;

        await Task.Run(async() =>
        {
            using (WebClient client = new WebClient())
            {
                client.DownloadProgressChanged += (obj, args) => progessChangedAction?.Invoke(args.ProgressPercentage);

                readedData = await client.DownloadDataTaskAsync(requestUri).ConfigureAwait(false);
            }
        });

        return readedData;

}