如何使用C＃SDK獲取訪問令牌

Question

我將Facebook SDK更新爲6.0.10，並且一些曾經工作的代碼不再工作。我曾經在用戶的牆上張貼使用下面的方法。

FacebookClient類用於採取AppId和AppSecret，我沒有給它提供我的應用程序的任何訪問令牌。

string uId = "SomeUid"; 
FacebookClient fb = new FacebookClient(AppId,AppSecret); 

string userFeedPath = String.Format("/{0}/feed", uId); 

dynamic parameters = new ExpandoObject(); 
parameters.link = "Test@test"; 
parameters.message = "test"; 

try 
{ 
    dynamic result = fb.Post(userFeedPath, parameters); 
} 
catch(Exception ex) 
{ 

} 

現在，即使我試試這個，

FacebookClient fb = new FacebookClient(); 

fb.AppId = "1234..."; 
fb.AppSecret = "76e69e0c334995cecc8c...."; 

我得到這個錯誤：

(OAuthException - #200) (#200) This API call requires a valid app_id.

我該如何解決這個問題？

Answer 1

您需要通過發出請求來獲取應用訪問令牌。

var fb = new FacebookClient(); 
dynamic result = fb.Get("oauth/access_token", new { 
    client_id  = "app_id", 
    client_secret = "app_secret", 
    grant_type = "client_credentials" 
}); 
fb.AccessToken = result.access_token; 

Answer 2

對於代碼 - >用戶接入令牌交換在服務器側流 - 代替（版本5）：

FacebookOAuthClient oAuthClient = new FacebookOAuthClient(); 
    oAuthClient.AppId = "..."; 
    oAuthClient.AppSecret = "..."; 
    oAuthClient.RedirectUri = new Uri("https://.../....aspx"); 

    dynamic tokenResult = oAuthClient.ExchangeCodeForAccessToken(code); 
    return tokenResult.access_token; 

現在使用（版本6）：

Dictionary<string, object> parameters = new Dictionary<string, object>(); 
    parameters.Add("client_id", "..."); 
    parameters.Add("redirect_uri", "https://.../....aspx"); 
    parameters.Add("client_secret", "..."); 
    parameters.Add("code", code); 

    result = fb.Get("/oauth/access_token", parameters); 

    string accessToken = result["access_token"]; 

（請參閱：http://developers.facebook.com/docs/authentication/server-side/）

Answer 3

我昨天剛剛開始使用此Facebook庫，並認爲缺乏賦予m訪問令牌沒有通過JavaScript傳遞是一個主要的缺點。這是一個可以獲取訪問令牌的助手。我希望這能幫助那些和我一樣遭受同樣挫折的人。我認爲這應該都很好。在我發現Facebook NuGet之前，我在網站上做了類似的工作，現在它已經運行了近一年。

如果有更好的方法，請讓我知道。

public class FacebookHelper 
{ 
    private string _appId; 
    private string _appSecret; 
    private string _accessToken; 

    public string AccessToken 
    { 
     get 
     { 
      if (_accessToken == null) 
       GetAccessToken(); 

      return _accessToken; 
     } 
     set { _accessToken = value; } 
    } 

    public FacebookHelper(string appId, string appSecret) 
    { 
     this._appId = appId; 
     this._appSecret = appSecret; 
    } 

    public string GetAccessToken() 
    { 
     var facebookCookie = HttpContext.Current.Request.Cookies["fbsr_" + _appId]; 
     if (facebookCookie != null && facebookCookie.Value != null) 
     { 
      string jsoncode = System.Text.ASCIIEncoding.ASCII.GetString(FromBase64ForUrlString(facebookCookie.Value.Split(new char[] { '.' })[1])); 
      var tokenParams = HttpUtility.ParseQueryString(GetAccessToken((string)JObject.Parse(jsoncode)["code"])); 
      _accessToken = tokenParams["access_token"]; 
      return _accessToken; 
     } 
     else 
      return null; 

     // return DBLoginCall(username, passwordHash, cookieToken, cookieTokenExpires, args.LoginType == LoginType.Logout, null); 
    } 

    private string GetAccessToken(string code) 
    { 
     //Notice the empty redirect_uri! And the replace on the code we get from the cookie. 
     string url = string.Format("https://graph.facebook.com/oauth/access_token?client_id={0}&redirect_uri={1}&client_secret={2}&code={3}", _appId, "", _appSecret, code.Replace("\"", "")); 

     System.Net.HttpWebRequest request = System.Net.WebRequest.Create(url) as System.Net.HttpWebRequest; 
     System.Net.HttpWebResponse response = null; 

     try 
     { 
      using (response = request.GetResponse() as System.Net.HttpWebResponse) 
      { 
       System.IO.StreamReader reader = new System.IO.StreamReader(response.GetResponseStream()); 

       string retVal = reader.ReadToEnd(); 
       return retVal; 
      } 
     } 
     catch 
     { 
      return null; 
     } 
    } 

    private byte[] FromBase64ForUrlString(string base64ForUrlInput) 
    { 
     int padChars = (base64ForUrlInput.Length % 4) == 0 ? 0 : (4 - (base64ForUrlInput.Length % 4)); 
     StringBuilder result = new StringBuilder(base64ForUrlInput, base64ForUrlInput.Length + padChars); 
     result.Append(String.Empty.PadRight(padChars, '=')); 
     result.Replace('-', '+'); 
     result.Replace('_', '/'); 
     return Convert.FromBase64String(result.ToString()); 
    } 
} 

Answer 4

我試過上面的一些樣本，只是發現動態不能用xamarin studio進行編譯。這是我做的。

public class AccessTokenModel 
{ 
    public string Access_Token { get; set;} 
} 

var fb = new FacebookClient(); 
var result = fb.Get ("oauth/access_token", new { 
    client_id  = App.FaceBookId, 
    client_secret = App.FacebookAppSecret, 
    grant_type = "client_credentials" 
}); 
var accessToken = Newtonsoft.Json.JsonConvert.DeserializeObject<AccessTokenModel> (result.ToString()); 

或

FBSession.ActiveSession.AccessTokenData.AccessToken; 

Answer 5

There is another method to make calls to the Graph API that doesn't require using a generated app access token. You can just pass your app id and app secret as the access_token parameter when you make a call:

https://graph.facebook.com/endpoint?key=value&access_token=app_id|app_secret

The choice to use a generated access token vs. this method depends on where you hide your app secret.

來自：https://developers.facebook.com/docs/facebook-login/access-tokens

var client = new FacebookClient($"{appId}|{appSecret}"); 

Answer 6

野兔是一個真正的工作方法：

protected override string QueryAccessToken(Uri returnUrl, string authorizationCode) 
     { 
      // Note: Facebook doesn't like us to url-encode the redirect_uri value 
      var builder = new UriBuilder("https://graph.facebook.com/oauth/access_token"); 
      builder.AppendQueryArgument("client_id", this.appId); 
      builder.AppendQueryArgument("redirect_uri", NormalizeHexEncoding(returnUrl.GetLeftPart(UriPartial.Path))); 
      builder.AppendQueryArgument("client_secret", this.appSecret); 
      builder.AppendQueryArgument("code", authorizationCode); 

      using (WebClient client = new WebClient()) 
      { 
       //Get Accsess Token 
       string data = client.DownloadString(builder.Uri); 
       if (string.IsNullOrEmpty(data)) 
       { 
        return null; 
       } 

       var parsedQueryString = HttpUtility.ParseQueryString(data); 
       return parsedQueryString["access_token"]; 
      } 
     } 
private static string NormalizeHexEncoding(string url) 
     { 
      var chars = url.ToCharArray(); 
      for (int i = 0; i < chars.Length - 2; i++) 
      { 
       if (chars[i] == '%') 
       { 
        chars[i + 1] = char.ToUpperInvariant(chars[i + 1]); 
        chars[i + 2] = char.ToUpperInvariant(chars[i + 2]); 
        i += 2; 
       } 
      } 
      return new string(chars); 
     }