Twitter API 1.1 Integration with MVC in c#

Twitter has recently stopped its support to its API version 1 from 11th June,2013. Many developers including me are using that API in our application which was retrieving tweets as per a given hash tag (#).
After done a bit of googling I found that there is no way but to move our application to the new Twitter API version 1.1
I feel the primary road block for using the new Twitter API is its OAuth authentication. I hardly found any site wrote much about this. Anyways, first I had to register my Application to get four keys which had been used for OAuth authentication. The registration site is
https://dev.twitter.com/apps

Now I had the four keys.

Consumer key
Consumer secret
Access token
Access token secret

I was all ready to start writing my OAuth authentication class now. Firstly, I added the four keys in my web.config file.

Then I created a class named TwitterHelper.cs as follows

using System.Net;
using System.Security.Cryptography;
using System.IO;

public class TwitterHelper
    {
        public const string OauthVersion = "1.0";
        public const string OauthSignatureMethod = "HMAC-SHA1";

        public Twitter(string consumerKey, string consumerKeySecret, string accessToken, string accessTokenSecret)
        {
            this.ConsumerKey = consumerKey;
            this.ConsumerKeySecret = consumerKeySecret;
            this.AccessToken = accessToken;
            this.AccessTokenSecret = accessTokenSecret;
        }

        public string ConsumerKey { set; get; }
        public string ConsumerKeySecret { set; get; }
        public string AccessToken { set; get; }
        public string AccessTokenSecret { set; get; }
        
        public string GetTweets(string twitterHashTag, int count)
        {
            string resourceUrl = string.Format("https://api.twitter.com/1.1/search/tweets.json");
            var requestParameters = new SortedDictionary();
            requestParameters.Add("q", twitterHashTag);
            requestParameters.Add("count", count.ToString());
            requestParameters.Add("result_type", "mixed");
            var response = GetResponse(resourceUrl, "GET", requestParameters);
            return response;
        }
 
        private string GetResponse(string resourceUrl, string methodName, SortedDictionary requestParameters)
        {
            ServicePointManager.Expect100Continue = false;
            WebRequest request = null;
            string resultString = string.Empty;
            
            request = (HttpWebRequest)WebRequest.Create(resourceUrl + "?" + requestParameters.ToWebString());
            request.Method = methodName;
            request.ContentType = "application/x-www-form-urlencoded";
            
            
            if (request != null)
            {
                var authHeader = CreateHeader(resourceUrl, methodName, requestParameters);
                request.Headers.Add("Authorization", authHeader);

                var response = (HttpWebResponse)request.GetResponse();
                using (var sd = new StreamReader(response.GetResponseStream()))
                {
                    resultString = sd.ReadToEnd();
                    response.Close();
                }
            }
            return resultString;
        }

        private string CreateOauthNonce()
        {
            return Convert.ToBase64String(new ASCIIEncoding().GetBytes(DateTime.Now.Ticks.ToString()));
        }

        private string CreateHeader(string resourceUrl, string methodName, SortedDictionary requestParameters)
        {
            var oauthNonce = CreateOauthNonce();
            // Convert.ToBase64String(new ASCIIEncoding().GetBytes(DateTime.Now.Ticks.ToString())); 
            var oauthTimestamp = CreateOAuthTimestamp();
            var oauthSignature = CreateOauthSignature(resourceUrl, methodName, oauthNonce, oauthTimestamp, requestParameters);
            //The oAuth signature is then used to generate the Authentication header. 
            const string headerFormat = "OAuth oauth_nonce=\"{0}\", oauth_signature_method=\"{1}\", " + "oauth_timestamp=\"{2}\", oauth_consumer_key=\"{3}\", " + "oauth_token=\"{4}\", oauth_signature=\"{5}\", " + "oauth_version=\"{6}\"";
            var authHeader = string.Format(headerFormat, Uri.EscapeDataString(oauthNonce), Uri.EscapeDataString(OauthSignatureMethod), Uri.EscapeDataString(oauthTimestamp), Uri.EscapeDataString(ConsumerKey), Uri.EscapeDataString(AccessToken), Uri.EscapeDataString(oauthSignature), Uri.EscapeDataString(OauthVersion));
            return authHeader;
        }
        private string CreateOauthSignature(string resourceUrl, string method, string oauthNonce, string oauthTimestamp, SortedDictionary requestParameters)
        {
            //firstly we need to add the standard oauth parameters to the sorted list 
            requestParameters.Add("oauth_consumer_key", ConsumerKey);
            requestParameters.Add("oauth_nonce", oauthNonce);
            requestParameters.Add("oauth_signature_method", OauthSignatureMethod);
            requestParameters.Add("oauth_timestamp", oauthTimestamp);
            requestParameters.Add("oauth_token", AccessToken);
            requestParameters.Add("oauth_version", OauthVersion);
            var sigBaseString = requestParameters.ToWebString();
            var signatureBaseString = string.Concat(method, "&", Uri.EscapeDataString(resourceUrl), "&", Uri.EscapeDataString(sigBaseString.ToString()));
            
            var compositeKey = string.Concat(Uri.EscapeDataString(ConsumerKeySecret), "&", Uri.EscapeDataString(AccessTokenSecret));
            string oauthSignature;
            using (var hasher = new HMACSHA1(Encoding.ASCII.GetBytes(compositeKey)))
            {
                oauthSignature = Convert.ToBase64String(hasher.ComputeHash(Encoding.ASCII.GetBytes(signatureBaseString)));
            }
            return oauthSignature;
        }
        private static string CreateOAuthTimestamp()
        {
            var nowUtc = DateTime.UtcNow;
            var timeSpan = nowUtc - new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
            var timestamp = Convert.ToInt64(timeSpan.TotalSeconds).ToString(); return timestamp;
        }
    }

    public static class Extensions
    {
        public static string ToWebString(this SortedDictionary source)
        {
            var body = new StringBuilder();
            foreach (var requestParameter in source)
            {
                body.Append(requestParameter.Key);
                body.Append("=");
                body.Append(Uri.EscapeDataString(requestParameter.Value));
                body.Append("&");
            } //remove trailing '&' 
            body.Remove(body.Length - 1, 1); return body.ToString();
        }
    }

For showing tweets in the View, I created a custom model class named TwitterModel.cs as follows

public class TwitterModel
    {
        public string Id { get; set; }
        public string Content { get; set; }
        public string AuthorName { get; set; }
        public string AuthorUrl { get; set; }
        public string ProfileImage { get; set; }
        public DateTime? Published { get; set; }
    }

That's all, I got ready to use the TwitterHelper class and TwitterModel class in my controller to retrieve the tweets as per the Twitter Hash Tag (#)

public ActionResult Index()
{
     List tweets = GetTweets("#twitter");
     return View(tweets);
}

public List GetTweets(string twitterHashTag)
        {
            
            List lstTweets = new List();

            // New Code added for Twitter API 1.1
            if (!string.IsNullOrEmpty(twitterHashTag))
            {
                var twitter = new TwitterHelper(ConfigurationManager.AppSettings["OauthConsumerKey"],
                                                                ConfigurationManager.AppSettings["OauthConsumerKeySecret"],
                                                                ConfigurationManager.AppSettings["OauthAccessToken"],
                                                                ConfigurationManager.AppSettings["OauthAccessTokenSecret"]);
                var response = twitter.GetTweets(evt.TwitterHashtag, 100);
                dynamic timeline = System.Web.Helpers.Json.Decode(response);
                foreach (var tweet in timeline)
                {
                    System.Web.Helpers.DynamicJsonArray tweetJson = tweet.Value as System.Web.Helpers.DynamicJsonArray;
                    if (tweetJson != null && tweetJson.Count() > 0)
                        foreach (System.Dynamic.DynamicObject item in tweetJson)
                        {
                            TwitterModel tModel = new TwitterModel();
                            tModel.Id = ((dynamic)item).id.ToString();
                            tModel.AuthorName = ((dynamic)item).user.name;
                            tModel.AuthorUrl = ((dynamic)item).user.url;
                            tModel.Content = ((dynamic)item).Text;
                            string publishedDate = ((dynamic)item).created_at;
                            publishedDate = publishedDate.Substring(0, 19);
                            tModel.Published = DateTime.ParseExact(publishedDate, "ddd MMM dd HH:mm:ss", null);

                            tModel.ProfileImage = ((dynamic)item).user.profile_image_url;
                            lstTweets.Add(tModel);
                        }
                  }
            }
            return lstTweets;
        }

Finally, everything is done, I bound the Model object in the View and was able to retrieve the tweets by twitter hashtag. User can search using other twitter parameter also and would be able to retrieve the tweets.

I got the reference for OAuth class from the following blog. Please go through it for more explanation
http://johnnewcombe.net/blog/post/12

References : http://johnnewcombe.net/blog/post/12