Post comment to facebook wall using asp.net - asp.net

Question

I have a website that I have registered as a facebook app - I now have an app ID.
My website is ASP.net C#. When the user clicks a button I'd like it to post a pre-defined message to their wall. I'm expecting Facebook to present a login dialog to the user - they login and grant publish permission to for my website app.
Does anyone have any sample code that would do this? I think I need to use the graph API but all the examples I've seen use PHP - which I know nothing about. I'm looking for an example that would use Java Script (of which I know almost nothing) or C# (beautiful!).
* Update *
I have managed to get the access_token. Now I make a call through the Facebook C# API to post to the wall. I get the error message:
(#803) Some of the aliases you requested do not exist: profile_id
I've stepped through the api code and found that it is trying to post to the following address: {https://graph.facebook.com/PROFILE_ID/feed}, the post data is: message=Sample+message+from+c%23+sdk&access_token=199209316768200|2.1avFTZuDGR4HJ7jPFeaO3Q__.3600.1302897600.1-100000242760733|R4DkNDf4JCb6B2F64n5TSQwBqvM
I'm pretty sure my token should be valid. Prior to requesting access token I requested publish_stream on the app authorization request as follows:
Response.Redirect ("https://www.facebook.com/dialog/oauth?client_id=" + myAppId + "&redirect_uri=" + myURL + "&scope=publish_stream");
The sdk code that actually makes the request is as follows:
private string MakeRequest(Uri url, HttpVerb httpVerb,
Dictionary<string, string> args)
{
if (args != null && args.Keys.Count > 0 && httpVerb == HttpVerb.GET)
{
url = new Uri(url.ToString() + EncodeDictionary(args, true));
}
HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
request.Method = httpVerb.ToString();
if (httpVerb == HttpVerb.POST)
{
string postData = EncodeDictionary(args, false);
ASCIIEncoding encoding = new ASCIIEncoding();
byte[] postDataBytes = encoding.GetBytes(postData);
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = postDataBytes.Length;
Stream requestStream = request.GetRequestStream();
requestStream.Write(postDataBytes, 0, postDataBytes.Length);
requestStream.Close();
}
try
{
using (HttpWebResponse response
= request.GetResponse() as HttpWebResponse)
{
StreamReader reader
= new StreamReader(response.GetResponseStream());
return reader.ReadToEnd();
}
}
Can anyone see what I'm doing wrong?
Many thanks,
Rob.

Answer 1

First of all, you need to take care of Authentication. You need to create an Application, and use OAuth to get hold of the access token. It's all described in the Authentication guide.
To post something to the user's wall, take a look at the Graph API under Publishing.
As a start, you could use Facebook's C# SDK

Answer 2

You could look to use a .NET library like http://facebooknet.codeplex.com/ to do this. There are a couple out there, I just remembered this one...
HTH.

Answer 3

I created a video showing how to do this using OG: http://www.markhagan.me/Samples/Grant-Access-And-Post-As-Facebook-User-ASPNet
In case you don't have time to watch the video, here is the full code:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Facebook;
namespace FBO
{
public partial class facebooksync : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
CheckAuthorization();
}
private void CheckAuthorization()
{
string app_id = "374961455917802";
string app_secret = "9153b340ee604f7917fd57c7ab08b3fa";
string scope = "publish_stream,manage_pages";
if (Request["code"] == null)
{
Response.Redirect(string.Format(
"https://graph.facebook.com/oauth/authorize?client_id={0}&redirect_uri={1}&scope={2}",
app_id, Request.Url.AbsoluteUri, scope));
}
else
{
Dictionary<string, string> tokens = new Dictionary<string, string>();
string url = string.Format("https://graph.facebook.com/oauth/access_token?client_id={0}&redirect_uri={1}&scope={2}&code={3}&client_secret={4}",
app_id, Request.Url.AbsoluteUri, scope, Request["code"].ToString(), app_secret);
HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
StreamReader reader = new StreamReader(response.GetResponseStream());
string vals = reader.ReadToEnd();
foreach (string token in vals.Split('&'))
{
//meh.aspx?token1=steve&token2=jake&...
tokens.Add(token.Substring(0, token.IndexOf("=")),
token.Substring(token.IndexOf("=") + 1, token.Length - token.IndexOf("=") - 1));
}
}
string access_token = tokens["access_token"];
var client = new FacebookClient(access_token);
client.Post("/me/feed", new { message = "markhagan.me video tutorial" });
}
}
}
}

Answer 4

I am using this http://facebooksdk.codeplex.com/ . I am using the latest stable release, easy to use. To comment, just post with /OBJECT_ID/comments for more, refer http://developers.facebook.com/docs/reference/api/#publishing and http://developers.facebook.com/docs/reference/api/post/

Answer 5

How about trying this API tha I recently developed to make integrating with Facebook easier.
Here is a code sample for you there's more documentation on the site.
Authenticating Users
Imports Branches.FBAPI
...
Dim SI As New SessionInfo("[application_id]","applicaiton_secret")
'Redirects user to facebooks
SI.AuthenticateUser("http://[my url]", New SessionInfo.PermissionsEnum(){SessionInfo.PermissionsEnum.email, SessionInfo.PermissionsEnum.read_stream}))
'Called when the user is returned to your page
Dim FSR = FS.ReadFacebooAuthResponse
Response.Write(FSR.Access_Token)
Response.Write(FSR.UserID)
Making Posts
Imports Branches.FBAPI
...
Dim SI As New SessionInfo("[access_token]"))
Dim Posts = New Functions.Posts(SI)
Dim P As New Post
P.name = "name of post"
P.message = "message"
P.link = "www.cnn.com"
P.caption = "my caption"
Posts.PublishCreate("[object ID to post to]", P)
Dim PostID = P.id
Getting stuff from the graph.
Dim SI As New SessionInfo("[access_token]"))
Dim Req New Functions.Requests(SI)
Dim User = Req.GetUserInfo("[optional user ID]")
Response.Write(U.name)