I am trying to develop an Facebook application (apps.facebook.com/some_app) using PHP where I need to present some information based on user's music interests. I found that its under "user_likes > games".
My problems are as follows:
$auth_url = "http://www.facebook.com/dialog/oauth?client_id="
. $app_id . "&redirect_uri="
. urlencode($canvas_page)
."&scope=user_likes";
http://MY_CANVAS_PAGE/?code=some base64 encoded letters
if(empty($code) && !isset($_REQUEST['error'])) {
$_SESSION['state'] = md5(uniqid(rand(), TRUE)); //CSRF protection
echo("<script> top.location.href='" . $auth_url . "'</script>");
}
$signed_request = $_REQUEST["signed_request"];
list($encoded_sig, $payload) = explode('.', $signed_request, 2);
$data = json_decode(base64_decode(strtr($payload, '-_', '+/')), true);
echo ("Welcome User: " . $data["user_id"]);
Also tried the code found in http://developers.facebook.com/blog/post/500/
but I am getting error when trying to get the debug info using
print_r($decoded_response);
stdClass Object ( [error] => stdClass Object ( [message] => An active
access token must be used to query information about the current user.
[type] => OAuthException [code] => 2500 ) )
To get user's public info, I have tried also the suggested example in PHP SDK
$facebook = new Facebook(array(
'appId' => MY_APP_ID, //registered facebook APP ID
'secret' => MY_SECRET, //secret key for APP
));
$fb_user = $facebook->getUser();
if($fb_user){
try {
$user_profile = $facebook->api('/me');
echo $user_profile['email'];
}
catch(FacebookApiException $e) {
$fb_user = null;
}
}
But no success. Can somebody explain me why I am getting this error and how to access the user's music interest properly. Probably I misunderstood the API.
Thanks
Deepak
Error 2500 means you have no access token or an app access token but are trying to access /me/
- 'me' is a placeholder for 'current user or page ID' so won't be valid without an access token for a user or page.
To access the user's list of likes you'll also need the user_likes
Permission when authorising them
The most likely causes i've seen for apps not being able to exchange the code
for an access token are:
redirect_uri
you used is to a folder or server root and is missing a trailing slash (i.e it's http://www.example.com
instead of http://www.example.com/
)redirect_uri
you used in the first call to the auth dialog wasn't precisely the same as the redirect_uri
you used in the call to exchagne the code for an access_tokenIf your auth flow is broken for some other reason and you can't figure it out from the SDK examples or the Authentication documentation, this could take a while for someone to talk you through because you may be missing some background knowledge necessary to understand their answers
For me, I was trying to get an auth token with php and found out that the 2500 error was due to an issue with file_get_contents
not returning anything. I could access the URL in my browser, but not by using file_get_contents
. I fixed it by using CURL instead as described here: https://stackoverflow.com/a/6325313.
The result was that I used the code from https://developers.facebook.com/docs/authentication/server-side/ and replaced the line:
$response = file_get_contents($token_url);
with
$ch = curl_init($token_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
It therefore became:
$token_url = "https://graph.facebook.com/oauth/access_token?client_id="
. $app_id . "&redirect_uri=" . urlencode($redirect_url)
. "&client_secret=" . $app_secret
. "&code=" . $code;
/* Facebook say to use this, but file_get_contents isn't working!
$response = file_get_contents($token_url,null, $val);
*/
// Use this as an alternative
$ch = curl_init($token_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
// From https://developers.facebook.com/docs/authentication/server-side/
$params = null;
parse_str($response, $params);
$access_token = $params['access_token'];
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