If you don’t already know, Facebook has opened up their data for some, regulated, 3rd party use. Facebook calls this their Open Graph API (application programming interface). Any developer who follows the specified steps can create applications that integrate with Facebook user data. Facebook does apply limitations on how developers can use the data in order to protect Facebook users. But, for the most part, if a Facebook user agrees, you can gain access to just about all of their profile data, and even post to their wall, etc.
Getting Started
Before you can start developing with Facebook you’ll need to register an application (yet to be developed) with Facebook. Start on the Facebook Developers page and then go to the Apps tab. I’m not going to go into detail about this because it’s pretty straight forward and already written about everywhere on the web. To make getting to the data easier there is a PHP SDK for Facebook Open Graph. We will be using this library for all of our Facebook queries.
Permissions
Before you can get to any data a user is going to first have to grant your application access to specific parts of their data. Facebook has different data and actions sectioned into permission groups. Below is an example of requesting permissions to get a user’s email address, bio data (name, etc), and to be able to read their wall.
$config = array(
‘appId’ => FBAPPID,
‘secret’ => FBAPPSECRET,
);
$facebook = new Facebook($config);
$fbuserid = $facebook->getUser();
$params = array(
“scope” => “read_stream,email,user_about_me”,
“redirect_uri” => “http://www.wescutshall.com/”
);
$loginurl = $facebook->getLoginUrl($params);
This will result in a variable, $loginurl, that you can use to create a hyperlink that points to Facebook and prompts the user to accept or deny the request for the specific permissions for your app. Assuming the user clicks “allow”, the user will be directed back to your website and you will now magically be able to query the information via the SDK. This $loginurl could replace your website’s “sign in” link if you wanted to simply force every user to have a Facebook account (and accept your app’s permissions). If a user has already given your application access to the data requested in the $loginurl url, Facebook will simply send the user to the redirect_uri, which should be your user dashboard/profile page. Some data, such as a user’s stream, is explicitly shown on a seperate permissions step on Facebook during the access granting process. A user will first allow you access to their bio data, and then they will allow or deny access to their stream. Should a user only allow access to their bio, and not their stream, the user will be bounced back to this permissions screen anytime your application attempts to access stream data. This actually integrates really nicely with web apps and keeps you from having to do constant error checking on data you’re asking for from Facebook.
Requesting Data
Below is an example of requesting the bio information:
//unique identifier on Facebook
$fbuserid = $facebook->getUser();
$user_profile = $facebook->api(‘/me’,'GET’);
$fname = $user_profile["first_name"];
$lname = $user_profile["last_name"];
$email = $user_profile["email"]; //this was a separate permission, remember?
Requesting wall/stream information:
$feed = $facebook->api(‘/me/feed’,'GET’);
for ($i=0;$i<count($feed["data"]);$i++)
{
// do something, like reading all shared links – $feed["data"][$i]["link"]
}
You could also check to see if a user has already liked your Facebook page:
$url = “/me/likes/$pageid”;
$like = $facebook->api($url,’GET’);
if($like["data"][0]["id"] != $pageid)
{
//do something, like suggest they like your page, or hide content until they do
}
This is just an intro into getting data from Facebook from PHP using the Open Graph API and Facebook PHP SDK. Facebook dogs and Google should be able to answer most of your questions.
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