Programmatically submit HTML form for browser-based upload

Question

I'm trying to upload a video from an c# web application to Youtube using API v2.0.

This is the documentation i found:

YouTube API 2.0 docs

I can accomplish AuthSub for web applications and send the video metadata to youtube; After that i can read the TOKEN and the URL needed to make the browser-based upload.

Now i've to fill this HTML form to perform the real upload.

<form action="post_url?nexturl=http://example.com" method ="post" enctype="multipart/form-data">
<input type="file" name="file"/>
<input type="hidden" name="token" value="token_value"/>
<input type="submit" value="go" />
</form>

I've searched the net for an example to how programatically "emulate" and send this html form from codebehind without luck.

This is my actual code only written for testing purpose:

  YouTubeRequestSettings settings = new YouTubeRequestSettings("TEST_APP", "DEVELOPER_KEY", "USERNAME", "PASSWORD");
        YouTubeRequest request = new YouTubeRequest(settings);


        Video newVideo = new Video();

        newVideo.Title = "My Test Movie";
        newVideo.Tags.Add(new MediaCategory("Autos", YouTubeNameTable.CategorySchema));
        newVideo.Keywords = "cars, funny";
        newVideo.Description = "My description";
        newVideo.YouTubeEntry.Private = false;
        newVideo.Tags.Add(new MediaCategory("mydevtag, anotherdevtag", YouTubeNameTable.DeveloperTagSchema));

        FormUploadToken token_youtube = request.CreateFormUploadToken(newVideo);
        string url_per_post_youtube = token_youtube.Url + "?nexturl=" + HttpContext.Current.Request.Url.AbsoluteUri + "test.aspx"; 

        byte[] fileBytes = File.ReadAllBytes("C:\\VIDEO.MOV");
        StringBuilder sb = new StringBuilder();

        foreach (byte b in fileBytes)
        {
            sb.Append(Convert.ToString(b, 2).PadLeft(8, '0'));
        }

        ASCIIEncoding encoding = new ASCIIEncoding();
        string postData = "token=" + token_youtube.Token.ToString();
        postData += ("&file=" + sb );
        byte[] data = encoding.GetBytes(postData);
        try
        {
            // Prepare web request...
            HttpWebRequest myRequest =
              (HttpWebRequest)WebRequest.Create(url_per_post_youtube);
            myRequest.Method = "POST";
            myRequest.ContentType = "multipart/form-data";
            myRequest.KeepAlive = true;
            myRequest.ContentLength = data.Length;
            Stream newStream = myRequest.GetRequestStream();
            // Send the data.
            newStream.Write(data, 0, data.Length);
            newStream.Close();

            string strResponse;
            StreamReader stIn = new StreamReader(myRequest.GetResponse().GetResponseStream());
            strResponse = stIn.ReadToEnd();
            stIn.Close();
        }
        catch (Exception ex)
        {
            string asd = ex.Message;
        }

With this code the youtube remote server reply with:

The remote server returned an error: (400) Bad Request

A 400 response code identifies a bad request. For example, you will receive a 400 response code if you submit a request to the wrong URL or include an unsupported or nonexistent parameter in your request. The API response content will explain the reason why the API returned a 400 response code

I cannot find the way to understand what is appenin'

Answer 1

So you need a way to understand what is appenin'? I think the best way is to use tools to find exactly what message you're sending to youtube.

fiddler is a very useful tool that monitors http traffic. With this you can see exactly what you're sending. Either you are not sending the message you think you are sending, or you are wrong about the form of the message you need to send. this should let you determine which one of these has happened.