500 px API与C＃引发500内部服务器错误

Question

I am trying to implement 500px API with C# . I am able to authenticate user with 500px API but I am unable to get the access_token in exchange of response_token which leaves my third step of Oauth 1.0 incomplete. I am able to authorize user and get oauth_token and oauth_verifier but when I use this oauth_token for making following request :-

       https://api.500px.com/v1/oauth/access_token

500 Internal Server Error along with the following screen gets thrown

I have debugged my code like thousand times, tried different ways to form URL, added various parameters to the request but no help. I am very badly stuck as almost no information is available on 500px developer website or on web for using this api in C#. I have reached a dead-end!
Following is my code:-

1.]For requesting token and authorizing user :-

        string normalizedUrl;
        string normalizedRequestParameters;
        OAuth.OAuthBase myOAuth = new OAuth.OAuthBase();
        try
        {
            Uri uri = new Uri("https://api.500px.com/v1/oauth/request_token");
           string  consumerKey = "u26X4av9ydNPd7kteT7bunfcdjHqVttYWIDOC1lA";
           string  consumerSecret = "73iaFPqCR4xkH3dgYIcPauTqhI6tMHWChDivnOP7";
            string timeStamp = myOAuth.GenerateTimeStamp();
            string nonce = myOAuth.GenerateNonce();
            myOAuth.includeVersion = true;
            string signature = myOAuth.GenerateSignature(uri, consumerKey, consumerSecret,
                                    "", "", "GET", timeStamp, nonce, OAuth.OAuthBase.SignatureTypes.HMACSHA1,
                                                 out normalizedUrl, out normalizedRequestParameters);

            string authorizationUrl = normalizedUrl + "?" + normalizedRequestParameters + "&oauth_signature=" + myOAuth.UrlEncode(signature);
                            Uri signInUrl = new Uri(authorizationUrl);



            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(signInUrl);

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();

            StreamReader stIn = new StreamReader(response.GetResponseStream());

            string responseString = stIn.ReadToEnd();

            stIn.Close();

            //oauth_token=cf40227bb7ede4d6e56ff790324761b3&oauth_token_secret=0bcb59dff2c1d095739c86c534fc62d7ed224fecfe8744d48c9c95f36211382f

            if (responseString.Contains("oauth_token=") && responseString.Contains("oauth_token_secret="))
            {
                String RespToken = responseString.Split('&')[0].Replace("oauth_token=", "");
                String RespSecret = responseString.Split('&')[1].Replace("oauth_token_secret=", "");

                uri = new Uri("https://api.500px.com/v1/oauth/authorize");
                timeStamp = myOAuth.GenerateTimeStamp();
                nonce = myOAuth.GenerateNonce();
                myOAuth.includeVersion = true;
                signature = myOAuth.GenerateSignature(uri, consumerKey, consumerSecret, RespToken

                    , RespSecret, "GET", timeStamp, nonce, OAuth.OAuthBase.SignatureTypes.HMACSHA1,

                    out normalizedUrl, out normalizedRequestParameters);
                Console.WriteLine("Signature=="+signature);
                authorizationUrl = normalizedUrl + "?" + normalizedRequestParameters + "&oauth_signature=" + myOAuth.UrlEncode(signature);

                Uri signInUrl1 = new Uri(authorizationUrl);
                webBrowser1.Navigate(signInUrl1);

}

2.]After User clicks on Authorise this application for getting access_token:-

     private void webBrowser_Navigated(object sender, WebBrowserNavigatedEventArgs e)
    {
        string parameters;
         string normalizedUrl;
        string normalizedRequestParameters;
        string consumerKey = "u26X4av9ydNPd7kteT7bunfcdjHqVttYWIDOC1lA";
        string consumerSecret = "73iaFPqCR4xkH3dgYIcPauTqhI6tMHWChDivnOP7";
        OAuth.OAuthBase myOAuth = new OAuth.OAuthBase();

         try

        {
           if (e.Url.ToString().Contains("https://www.xyz.com/"))
            {
                String url = (e.Url.ToString()).Replace("https://www.xyz.com/?","");

                if( url.Contains("oauth_token="))
                {
                  string OAuthToken = url.Split('&')[0].Replace("oauth_token=", "");
                  var uri = "https://api.500px.com/v1/oauth/access_token";
                  OAuthBase oAuth = new OAuthBase();
                  var nonce = oAuth.GenerateNonce();
                  var timeStamp = oAuth.GenerateTimeStamp();                
                  var signature = oAuth.GenerateSignature(new Uri(uri), consumerKey, consumerSecret,
                  OAuthToken, String.Empty, "POST", timeStamp, nonce,
                  OAuthBase.SignatureTypes.HMACSHA1, out normalizedUrl, out  normalizedRequestParameters);
                  signature = HttpUtility.UrlEncode(signature);
                  var requestUri = normalizedUrl + "?" + "oauth_callback=https://www.xyz.com" +"?"+ normalizedRequestParameters + "&oauth_signature=" + myOAuth.UrlEncode(signature);
                  Console.WriteLine(requestUri);


                  var request = (HttpWebRequest)WebRequest.Create(requestUri.ToString());
                  request.Method = WebRequestMethods.Http.Post;
                  request.ContentType = "application/json";
                //  request.ContentType = "application / x - www - form - urlencoded";
                  //request.Credentials = CredentialCache.DefaultCredentials;
                  //request.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)";
                  var response = request.GetResponse();
                  var reader = new StreamReader(response.GetResponseStream());
                  var accessToken = reader.ReadToEnd();
                    }
                    }
            catch(Exception ex)
            {
              Console.Writeln(ex.toString());
            }
            }

Now following is the line where my code is breaking:-

         var response = request.GetResponse();

Completely at my wits end on this issue, not able to get to the root of it. Any help any directions will be highly appreciated. Any suggestions would be of great help!!
Thanks a ton in advance!

Answer 1

Here's what to do:

1. Use GET rather than POST (POST may work; I've not tried it and have had little success with 500px and POSTing)

2. Include the oauth_verifier you received during the authorisation step in the query URL

3. Sign the entire query using your consumer key and request token secret (returned in step 1)

Code snippet which should return "oauth_token=...&oauth_token_secret=..." in the HTTP reply body.

Make sure your OAuth implementation doesn't strip out any parameters beginning with "oauth_"! Mine was and it was stripping out the oauth_verifier parameter which is required by 500px.

        OAuth.OAuthBase oauth = new OAuth.OAuthBase();

        string strUrl = "";
        string strParams = "";

        string signature = oauth.GenerateSignature(new Uri(API_URL + "oauth/access_token?oauth_verifier=" + this.oauthVerifier),
                                            this.consumerKey, this.consumerSecret, this.oauthToken, this.requestTokenSecret,
                                            "GET", oauth.GenerateTimeStamp(), oauth.GenerateNonce(),
                                            OAuth.OAuthBase.SignatureTypes.HMACSHA1,
                                            out strUrl, out strParams);

        string authorizationUrl = strUrl + "?" + strParams + "&oauth_signature=" + System.Web.HttpUtility.UrlEncode(signature);
        Debug.WriteLine("url>" + authorizationUrl);

        Response reply = SendGetRequest(authorizationUrl);
        if (reply.Success)
        {
            Debug.WriteLine("access_token>" + reply.Content);