Linq-To-Twitter Bad Authentication

Question

So i've been using Linq-To-Twitter to add Twitter Integration to my Windows 8 Store App, Moreso for playing around with it, but i've come accross a problem. My current authentication codeblock is

  var auth = new WinRtAuthorizer
        {
            Credentials = new LocalDataCredentials
            {
                ConsumerKey = "",
                ConsumerSecret = ""
            },
            UseCompression = true,
            Callback = new Uri("http://linqtotwitter.codeplex.com/")
        };

        if (auth == null || !auth.IsAuthorized)
        {
            await auth.AuthorizeAsync();
        }

Which works great, unless I go into the authentication screen and click the back button on the top left, to exit authentication without supplying details. at which point i get a TwitterQueryException: Bad Authentication data at:

                var timelineResponse =
                 (from tweet in twitterCtx.Status
                  where tweet.Type == StatusType.Home
                  select tweet)
                 .ToList();

Obviously because the Authentication Information was wrong, I'm trying to find a way to stop proceeding to the rest of the code if the authentication fails/is backed out.

I've tried simple boolean checks to no effect. I've been melting my brain over this for hours, so any help would be greatly appreciated. Thanks a bunch!

Answer 1

You can query Account.VerifyCredentials to ensure the user is logged in before performing any other operation. Here's an example:

        const int BadAuthenticationData = 215;

        var twitterCtx = new TwitterContext(auth);

        try
        {
            var account =
                (from acct in twitterCtx.Account
                 where acct.Type == AccountType.VerifyCredentials
                 select acct)
                .SingleOrDefault();

            await new MessageDialog(
                "Screen Name: " + account.User.Identifier.ScreenName, 
                "Verification Passed")
                .ShowAsync();
        }
        catch (TwitterQueryException tqEx)
        {
            if (tqEx.ErrorCode == BadAuthenticationData)
            {
                new MessageDialog(
                    "User not authenticated", 
                    "Error During Verification.")
                    .ShowAsync();
                return;
            }

            throw;
        }

Your error handling strategy will differ from this, which is just a sample, but it shows you how to know that the error occurred and gives you the opportunity to react to the problem before resuming normal operation.

TwitterQueryException will include the Twitter error code in the ErrorCode property. It also sets Message to the error message that Twitter returns. InnerException provides the underlying exception with the original stack trace, which is often a WebException thrown because of the HTTP error code returned from Twitter.