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Question

Good afternoon, I'm using version 5.4.1 of the Facebook C# SDK. I should note that I am using the source code directly rather than the DLLs (in case this makes any difference).

So the fact that filter attributes are setup is awesome (thank you dev team :).

My issue is occurring during the initial request (before I get to using verifying the GET response from Facebook)

Here is my initial request:

dynamic result = fb.Post(
                string.Format("/{0}/subscriptions", 
                     FacebookApplication.Current.AppId),
                new Dictionary<string, object>
                    {
                        {"object", "user"},
                        {"fields", "friends"},
                        {
                            "callback_url",
                            "http://localhost:16917/subscription/verify"
                            },
                        {
                            "verify_token",
                            "77FB802F-1147-48F0-BB0F-E4E9BC1FBCFC"
                            }
                    });

I'm finding that an exception is internally being thrown and via Fiddler I'm seeing that the request is never going out. The exception is:

$exception  {"(OAuthException) (#15) This method must be called with an app access_token."} System.Exception {Facebook.FacebookOAuthException}

I initially thought this may be related to Facebook.FacebookClient's PrepareRequest method:

if (httpMethod == HttpMethod.Get)
{
    // for GET, all parameters goes as querystrings
    input = null;
    queryString.Append(FacebookUtils.ToJsonQueryString(parameters));
}
else
{
    if (parameters.ContainsKey("access_token"))
    {
        queryString.AppendFormat("access_token={0}", parameters["access_token"]);
        parameters.Remove("access_token");
    }
}

but commenting out the line parameters.Remove("access_token"); made no difference.

Any help would be greatly appreciated!

Answer 1

What access_token are you using?

Are you using a User's access token, or an App access token?

If you are using an User's access token take a look here http://developers.facebook.com/docs/authentication/#app-login on how to get an App access token.

Answer 2

You will need to use the app access_token.

You can easily create an app access_token using the following constructor.

var fb = new FacebookClient("appid", "appsecret");
dynamic result = fb.Post( .... );