Question

I have been looking through quite a few posts on StackOverflow and on the internet on being able to log a user out of Facebook through an ASP.NET LinkButton.

I have tried implementing solutions from the following posts:

• Facebook Logout button in asp.net web application
• How to logout from facebook connect in asp.net?
• Facebook Logout Confusion

Code

ASPX Page

<asp:LinkButton ID="LogoutButton" CssClass="log-out fb"  OnClick="LogoutButton_Click" runat="server">Logout</asp:LinkButton>

JavaScript

$(".log-out.fb").click(function () {
    FB.logout(function (response) {
        //Logged out
        FB.Auth.setAuthResponse(null, 'unknown');
    });
});

HTML Output

<a id="MainContent_LogoutButton" class="log-out fb" href="javascript:__doPostBack('ctl00$MainContent$LogoutButton','')" style="width: 66px; ">Logout</a>

I definitely know that the jQuery click event is getting fired when debugging via Firebug. The jQuery code works fine when used in conjunction with a standard HTML anchor, so there is no reason for it not to work on a ASP.NET LinkButton.

Any help would be appreciated.

Answer 1

Thanks for all your help. But I managed to find a way to log out a user by using the following link:

https://www.facebook.com/logout.php?next=YOUR_URL&access_token=ACCESS_TOKEN

I created a callback page similar to the one from this article. Once I received the “access token”, I managed to log the user out.

Here is my code for my callback page:

protected void Page_Load(object sender, EventArgs e)
{
    if (!String.IsNullOrEmpty(Request["code"]) && !Page.IsPostBack)
    {
        FacebookCallback();
    }
}

private void FacebookCallback()
{
    var client = new RestClient { Authority = "https://graph.facebook.com/oauth/" };
    var request = new RestRequest { Path = "access_token" };

    request.AddParameter("client_id", ConfigurationManager.AppSettings["facebook.appid"]);
    request.AddParameter("redirect_uri", ConfigurationManager.AppSettings["facebook.logout.callbackurl"]);
    request.AddParameter("client_secret", ConfigurationManager.AppSettings["facebook.appsecret"]);
    request.AddParameter("code", Request["code"]);

    RestResponse response = client.Request(request);
    // A little helper to parse the querystrings.
    StringDictionary result = QueryStringHelper.ParseQueryString(response.Content);

    string aToken = result["access_token"];

    LogUserOut(aToken);
}

private void LogUserOut(string sToken)
{
    string url = String.Format("https://www.facebook.com/logout.php?next=http://{0}/Default.aspx&access_token={1}", ConfigurationManager.AppSettings["site.url"], sToken);

    Response.Redirect(url);
}

I hope this helps others if they encounter the same issue.