Facebook Apps and Windows Azure Web Sites (Part 1 – Getting Started)

AccountController.cs

public class AccountController : Controller
{
    //
    // GET: /Account/Login

    public ActionResult Login()
    {
        // Build the Return URI form the Request Url
        var redirectUri = new UriBuilder(Request.Url);
        redirectUri.Path = Url.Action("FbAuth", "Account");

        var client = new FacebookClient();

        // Generate the Facebook OAuth URL
        // Example: https://www.facebook.com/dialog/oauth?
        //                client_id=YOUR_APP_ID
        //               &redirect_uri=YOUR_REDIRECT_URI
        //               &scope=COMMA_SEPARATED_LIST_OF_PERMISSION_NAMES
        //               &state=SOME_ARBITRARY_BUT_UNIQUE_STRING
        var uri = client.GetLoginUrl(new
        {
            client_id = ConfigurationManager.AppSettings["FacebookAppId"],
            redirect_uri = redirectUri.Uri.AbsoluteUri,
            scope = "email",
        });

        return Redirect(uri.ToString());
    }
}

AppController.cs

[Authorize]
public class AppController : Controller
{
    //
    // GET: /App/

    public ActionResult Index()
    {
        return View();
    }

}

FbAuth.cs

public ActionResult FbAuth(string returnUrl)
{
    var client = new FacebookClient();
    var oauthResult = client.ParseOAuthCallbackUrl(Request.Url);

    // Build the Return URI form the Request Url
    var redirectUri = new UriBuilder(Request.Url);
    redirectUri.Path = Url.Action("FbAuth", "Account");

    // Exchange the code for an access token
    dynamic result = client.Get("/oauth/access_token", new
    {
        client_id = ConfigurationManager.AppSettings["FacebookAppId"],
        redirect_uri = redirectUri.Uri.AbsoluteUri,
        client_secret = ConfigurationManager.AppSettings["FacebookAppSecret"],
        code = oauthResult.Code,
    });

    // Read the auth values
    string accessToken = result.access_token;
    DateTime expires = DateTime.UtcNow.AddSeconds(Convert.ToDouble(result.expires));

    // Get the user's profile information
    dynamic me = client.Get("/me", 
                  new { 
                     fields = "first_name,last_name,email", 
                     access_token = accessToken 
                  });

    // Read the Facebook user values
    long facebookId = Convert.ToInt64(me.id);
    string firstName = me.first_name;
    string lastName = me.last_name;
    string email = me.email;

    // Add the user to our persistent store
    var userService = new UserService();
    userService.AddOrUpdateUser(new User
    {
        Id = facebookId,
        FirstName = firstName,
        LastName = lastName,
        Email = email,
        AccessToken = accessToken,
        Expires = expires
    });

    // Set the Auth Cookie
    FormsAuthentication.SetAuthCookie(email, false);

    // Redirect to the return url if availible
    if (String.IsNullOrEmpty(returnUrl))
    {
        return Redirect("/App");
    }
    else
    {
        return Redirect(returnUrl);
    }
}

InstallPackage.ps

Install-Package Facebook

Web.config

<appSettings>
  ...
  <add key="FacebookAppId" value="your_local_app_id"/>
  <add key="FacebookAppSecret" value="your_local_app_secret" />
</appSettings>

Web.Release.config

<appSettings>
<add key="FacebookAppId" value="your_prod_app_id"
     xdt:Transform="SetAttributes" xdt:Locator="Match(key)"/>
<add key="FacebookAppSecret" value="your_prod_app_secret"
     xdt:Transform="SetAttributes" xdt:Locator="Match(key)" />
</appSettings>