how to post to facebook page wall from .NET

Question

I\'ve created Facebook page. I have no application secret and no access token.

I want to post to this page from my .NET desktop application. How can I do it? Can any

Answer 1

You can use https://www.nuget.org/packages/Microsoft.Owin.Security.Facebook/ to obtain users login and permission and https://www.nuget.org/packages/Facebook.Client/ to post to feeds.

Below example is for ASP.NET MVC 5:

public void ConfigureAuth(IAppBuilder app)
        {
            app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

            // Facebook 
            var facebookOptions = new FacebookAuthenticationOptions
            {
                AppId = "{get_it_from_dev_console}",
                AppSecret = "{get_it_from_dev_console}",
                BackchannelHttpHandler = new FacebookBackChannelHandler(),
                UserInformationEndpoint = "https://graph.facebook.com/v2.4/me?fields=id,name,email,first_name,last_name,location",
                Provider = new FacebookAuthenticationProvider
                {
                    OnAuthenticated = context =>
                    {
                        context.Identity.AddClaim(new Claim("FacebookAccessToken", context.AccessToken)); // user acces token needed for posting on the wall 
                        return Task.FromResult(true);
                    }
                }
            };
            facebookOptions.Scope.Add("email");
            facebookOptions.Scope.Add("publish_actions"); // permission needed for posting on the wall 
            facebookOptions.Scope.Add("publish_pages"); // permission needed for posting on the page
            app.UseFacebookAuthentication(facebookOptions);

            AntiForgeryConfig.UniqueClaimTypeIdentifier = ClaimTypes.NameIdentifier;
        }
    }

On the callback you get user access token:

public ActionResult callback()
{
    // Here we skip all the error handling and null checking
    var auth = HttpContext.GetOwinContext().Authentication;
    var loginInfo = auth.GetExternalLoginInfo();
    var identityInfo = auth.GetExternalIdentity(DefaultAuthenticationTypes.ExternalCookie);

    var email = loginInfo.Email // klaatuveratanecto@gmail.com
    var name = loginInfo.ExternalIdentity.Name  // Klaatu Verata Necto
    var provider = loginInfo.Login.LoginProvider // Facebook | Google

    var fb_access_token = loginInfo.identityInfo.FindFirstValue("FacebookAccessToken");
    // Save this token to database, for the purpose of this example we will save it to Session.
    Session['fb_access_token'] = fb_access_token;
    // ...                   
}

Which then you can use to post to user's feed or page

public class postcontroller : basecontroller
{                      
        public ActionResult wall()
        {
            var client = new FacebookClient( Session['fb_access_token'] as string);
            var args = new Dictionary();
            args["message"] = "Klaatu Verata N......(caugh, caugh)";

            try
            {
                client.Post("/me/feed", args); // post to users wall (feed)
                client.Post("/{page-id}/feed", args); // post to page feed
            }
            catch (Exception ex)
            {
                // Log if anything goes wrong 
            }

        }
}

I posted full example over here: https://klaatuveratanecto.com/facebook-wall-feed-posting-asp-net-mvc/