Accessing Google Docs with GData

Question

Working Platform: ASP.NET 4.0 C# ( Framework Agnostic )

Google GData is my dependency

using Google.GData.Client;
using Google.GData.Extensions;
using Google.GData.Documents;

I have two pages Auth and List.

Auth redirects to Google Server like this

public ActionResult Auth()
{
    var target = Request.Url.ToString().ToLowerInvariant().Replace("auth", "list");
    var scope = "https://docs.google.com/feeds/";
    bool secure = false, session = true;

    var authSubUrl = AuthSubUtil.getRequestUrl(target, scope, secure, session);
    return new RedirectResult(authSubUrl);
}

Now it reaches the List Page if Authentication is successful.

public ActionResult List()
{
    if (Request.QueryString["token"] != null)
    {
        String singleUseToken = Request.QueryString["token"];

        string consumerKey = "www.blahblah.net";
        string consumerSecret = "my_key";
        string sessionToken = AuthSubUtil.exchangeForSessionToken(singleUseToken, null).ToString(); 

        var authFactory = new GOAuthRequestFactory("writely", "qwd-asd-01");
        authFactory.Token = sessionToken;
        authFactory.ConsumerKey = consumerKey;
        authFactory.ConsumerSecret = consumerSecret;
        //authFactory.TokenSecret = "";
        try
        {
            var service = new DocumentsService(authFactory.ApplicationName) { RequestFactory = authFactory };

            var query = new DocumentsListQuery();
            query.Title = "project";

            var feed = service.Query(query);
            var result = feed.Entries.ToList().ConvertAll(a => a.Title.Text);
            return View(result);
        }
        catch (GDataRequestException gdre)
        {
            throw;
        }
    }
}

This fails at the line var feed = service.Query(query); with the error

Execution of request failed: https://docs.google.com/feeds/default/private/full?title=project

The HttpStatusCode recieved on the catch block is HttpStatusCode.Unauthorized

What is wrong with this code? Do I need to get TokenSecret? If so how?

Answer 1

Used the 3-legged OAuth in the Google Data Protocol Client Libraries

Sample Code

string CONSUMER_KEY = "www.bherila.net";
string CONSUMER_SECRET = "RpKF7ykWt8C6At74TR4_wyIb";
string APPLICATION_NAME = "bwh-wssearch-01";

string SCOPE = "https://docs.google.com/feeds/";

public ActionResult Auth()
{
    string callbackURL = String.Format("{0}{1}", Request.Url.ToString(), "List");
    OAuthParameters parameters = new OAuthParameters()
    {
        ConsumerKey = CONSUMER_KEY,
        ConsumerSecret = CONSUMER_SECRET,
        Scope = SCOPE,
        Callback = callbackURL,
        SignatureMethod = "HMAC-SHA1"
    };

    OAuthUtil.GetUnauthorizedRequestToken(parameters);
    string authorizationUrl = OAuthUtil.CreateUserAuthorizationUrl(parameters);
    Session["parameters"] = parameters;
    ViewBag.AuthUrl = authorizationUrl;
    return View();
}

public ActionResult List()
{
    if (Session["parameters"] != null)
    {
        OAuthParameters parameters = Session["parameters"] as OAuthParameters;
        OAuthUtil.UpdateOAuthParametersFromCallback(Request.Url.Query, parameters);

        try
        {
            OAuthUtil.GetAccessToken(parameters);

            GOAuthRequestFactory authFactory = new GOAuthRequestFactory("writely", APPLICATION_NAME, parameters);

            var service = new DocumentsService(authFactory.ApplicationName);
            service.RequestFactory = authFactory;

            var query = new DocumentsListQuery();
            //query.Title = "recipe";

            var feed = service.Query(query);
            var docs = new List<string>();
            foreach (DocumentEntry entry in feed.Entries)
            {
                docs.Add(entry.Title.Text);
            }
            //var result = feed.Entries.ToList().ConvertAll(a => a.Title.Text);
            return View(docs);
        }
        catch (GDataRequestException gdre)
        {
            HttpWebResponse response = (HttpWebResponse)gdre.Response;

            //bad auth token, clear session and refresh the page
            if (response.StatusCode == HttpStatusCode.Unauthorized)
            {
                Session.Clear();
                Response.Write(gdre.Message);
            }
            else
            {
                Response.Write("Error processing request: " + gdre.ToString());
            }
            throw;
        }
    }
    else
    {
        return RedirectToAction("Index");
    }
}

This 2-legged sample never worked for me for google docs.