Jan 06 2010
Facebook Connect Tutorial
This tutorial will guide you to the process of integration of your web community with Facebook. This means that when a visitor comes to your site it can log in with normal credenditals if it has, but if it has not it can click on the “facebook connect” button and try to log in with its facebook account, automatically.
This is a good thing because, of course, your community is not so big and famous that every visitor wants to register and become a user to leave just a comment, but probably your visitors already have a Facebook account. So why loose their comments?
More: you can use facebook connected users to post automatically on users’s facebook walls, that is to say, you can increase your traffic.
The target is to add facebook connect functionality with small changes to your code, we also want to make very small changes to your database and to your normal login process.
INDEX, SEVEN STEPS:
1. Create an application on Facebook
2. Copy on your site the xd_receiver.htm file
3. Download the PHP apis for facebook and copy them to your site
4. Modify your users’ table
5. Create a PHP page for log in with facebook connect
6. Link the fbclogin.php file to your login
7. Further implementations in the next posts/pages of this blog
So let’s start:
STEP 1. Create an application on Facebook
This means that you have to be registered and logged-in on Facebook, than you have to go to the developer page on facebook and click on the “set up new application” button.
In the set up page you have different fields to enter, but only these ones are needed to make a facebook-connect application for our purpose:
a. “name of the application” and your developer contact in the Main Panel;
b. “Connect url” in the Facebook Connect Panel, you should enter the root of your community site, for the example: http://www.your-site-url.com
c. you can customize log (not necessary)
Save the changes.
This will create a couple of keys that you will use inside your PHP login page: API Key and secret. Copy them or leave this window open to copy them later.
STEP 2. Copy on your site the xd_receiver.htm file
This file is also called “cross domain communication channel” and it’s a static file which include some javascript from facebook servers. The job of this file is set up cookie of Facebook on your domain. It’s necessary because cookies are linked to the domain of the site that write them, so Facebook cannot add cookies on your site without this. And cookies are necessary because the PHP script that will do the work will read cookies setted up by this file. Your site will call facebook, facebook will ask for password if the user isn’t yet logged in, and facebook will call xd receiver to set up cookies on your domain. Finally PHP script will read the cookie that say “logged on facebook ok!”.
Here is the xd receiver file: (you can find it here)
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Cross-Domain Receiver Page</title> </head> <body> <script src="http://static.ak.connect.facebook.com/js/api_lib/v0.4/XdCommReceiver.js?2" type="text/javascript"></script> </body> </html>
STEP 3. Download the PHP apis for facebook and copy them to your site
You can download the PHP API here on Facebook servers.
You can find the previous link in the get started page of Facebook developers page.
STEP 4. Modify your users’ table
This is important: we want to let connect the guys of facebook, but we also want to make new users, so we create new users on our community for every new guy coming from facebook. We suppose that you already have a users’ table on your db:
TABLE users (something like this):
id ID INT AUTOINCREMENT PRIMARY
username VARCHAR
password VARCHAR
email VARCHAR
status ENUM ('active','pending','deactivated')
activationdate DATETIME
If you have the primary key on the email field, than you will have to remove it and use an autoincrement key because you will not receive the email from facebook, the users coming from facebook do not have the email field filled at the beginning. So they are “different”.
Add those fields to your users table:
fb_userid VARCHAR
fl_facebook ENUM ('new','normal','registered') DEFAULT = 'registered'
the fb_userid will store the facebook user id.
the fl_facebook is a flag and the values can be:
registered = is the default value that identify your users normally registered on your db
new = for new users just created
normal = for users that have been transformed into normal users (this could happen later, when you will ask the email to those users to make some action that only registered users can make on your site… for example buy a thing, subscribe to a newsletter, create a new item…), when they become ‘normal’ they are no longer ‘different’.
STEP 5.create a PHP page for log in with facebook connect
Here it is the code of the facebook login file (fbclogin.php), put it on your web site root (below some note) and read it because it’s full of comments:
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:fb="http://www.facebook.com/2008/fbml">
<head>
<script src="http://static.new.facebook.com/js/api_lib/v0.4/FeatureLoader.js.php" type="text/javascript"></script>
</head>
<body>
<?
//
// this file includes FB_API_KEY and FB_SECRET constants and the ConnectDB function
// to connect to your mysql database.
include("settings-and-functions.php");
//
// the php facebook api downloaded at step 3
include("fb/php/facebook.php");
if(!ConnectDB()) die;
//
// start facebook api with the codes defined in step 1.
$fb=new Facebook( FB_API_KEY , FB_SECRET );
$fb_user=$fb->get_loggedin_user();
$out="";
if($fb_user) {
//
// if we already have a user ID cookie than we link
// in the database this user with his facebook account
// using the fb_userid field.
// this code assumes that when a user login in your
// community you set up a value in a cookie called "myid".
// this cookie is the one that you use when you want
// to remember the user:
if ($_COOKIES["myid"]) {
$rs = mysql_query( "select * from users where id <>'".$_COOKIES["myid"]."' and fb_userid='".$fb_user."'" );
$r = mysql_fetch_array($rs);
mysql_query("update users set fb_userid='{$fb_user}' where id='".$_COOKIES["myid"]."'");
}
//
// with the user id from facebook retrived with the API,
// search for a user already registered with this process:
$rs = mysql_query( "select * from users where fb_userid='$fb_user'" );
if (mysql_num_rows($rs)) $u = mysql_fetch_array($rs); else $u="";
if (is_array($u)) {
//
// this is a user connected with facebook
// and already existing on your community.
// So, log in automatically with user and password of
// your community. These lens print a form and submit it
// to your real login page:
// (change the address in the action to match your normal login page)
$out.="log in...";
$out.="<form id='loginform' method='post' action=\"http://www.your-site-url.com/login.php\">";
$out.="<input type='hidden' name='user' value=\"".$u['username']."\"/>";
$out.="<input type='hidden' name='pass' value=\"".$u['password']."\"/>";
$out.="</form>";
$out.="<script type=\"text/javascript\">document.getElementById('loginform').submit();</script>";
} else {
//
// this is a user logged in on facebook
// but it doesn't exists on your community,
// it's new!
// So let's create automatically the user and log in!
$out = '<fb:profile-pic class="fb_profile_pic_rendered FB_ElementReady"' .
'facebook-logo="true" size="square" uid="' . $fb_user . '"></fb:profile-pic>';
//
// get some user details from facebook api
$user_details = $fb->api_client->users_getInfo($fb_user, array('last_name','first_name'));
//
// write out some message to welcome the new user:
$out.= $user_details[0]['first_name']." ".$user_details[0]['last_name'].", welcome on your-site-url.com<br/>";
$out.= "creating your account on your-site-url.com... wait...";
$tempuser = preg_replace("/[^a-z0-9]/i","",strtolower( $user_details[0]['first_name'].$user_details[0]['last_name'] ));
$found = false;
$i=0;
while (!$found) {
//
// search for a valid username
// not already used in your community
// this username is created with first name and last name
// from facebook and with a counter:
$user = $tempuser.($i==0?"":$i);
$rs = mysql_query("select count(*) from users where username='$user'");
$c = mysql_fetch_row($rs);
if ( $c[0] >0 ) $i++; else $found = true;
}
//
// generate random password for new user:
$pass = "fb".rand(1000,2000);
//
// empty email:
$email = "";
//create the user on your table
$sql = "INSERT INTO users (" .
"username, password, name, surname, email, status, activationdate, fb_userid, fl_facebook".
") VALUES ('{$user}','{$pass}','".addslashes($user_details[0]['first_name'])."',".
"'".addslashes($user_details[0]['last_name'])."','".$email."',".
"'active',NOW(),'','".
$fb_user."','new')";
mysql_query($sql);
//
// new user created, log him in:
$out.="log in...";
$out.="<form id='loginform' method='post' action=\"http://www.your-site-url.com/login.php\">";
$out.="<input type='hidden' name='user' value=\"".$user."\"/>";
$out.="<input type='hidden' name='pass' value=\"".$pass."\"/>";
$out.="</form>";
$out.="<script type=\"text/javascript\">document.getElementById('loginform').submit();</script>";
}
} else {
//
// the user probably isn't logged in on facebook, put out
// the facebook button and clicking on it it will open a pop uo
// that requires the login on facebook to proceed.
// the "onlogin" command refresh the page.
$out = '
<div">Click to log on your-site-url.com with your facebook account.<br/><fb:login-button size="medium" onlogin="document.location.href=document.location.href;"></fb:login-button><br/>
</div>';
}
?>
<?=$out?>
<script type="text/javascript"> FB.init("<?=FB_API_KEY?>", "/xd_receiver.htm"); </script>
</body>
</html>
This PHP file includes in the header some tag for facebook (the namespace declaration in the html tag), so it can handle FBML code (the facebook specific tags for html facebook elements).
Than it includes a javascript file from facebook which is called at the end with FB.init javascript call.
STEP 6. Link the fbclogin.php file to your login
Near your login fields, add a link to the fbclogin.php file so users will notice suddenly that you give a facebook connect functionality.
STEP 7. further implementations in the next posts
a. copy the avatar from facebook to your server: it’s easy: note, this is not approved by Facebook policies!
b. handle redirect to the correct page: if you have the login in every page you can modify this code to let the user go back to the correct page after the login process.
c. handle duplicated accounts: sometimes a user that connect with facebook already has an account on your site, so you will have two users for the same person on your db. That could be a problem, we will explain why and how to solve the problem.
d. handle registration completed: registration is completed when a user give you every data you consider mandatory, such as the email. This script already handles the flag fl_facebook, but in a further post we will explain how to modify your scripts to handle this part of the process.
e. use facebook connect functions to post to users wall on facebook: this will increase traffic to your site.
January 13th, 2010 9:00 pm
Thanks, ha! Where’s the subscribe button?
January 14th, 2010 10:34 pm
Generally I do not post on blogs, but I would like to say that this article really forced me to do so! Thanks, really nice blog.
January 19th, 2010 8:01 pm
[...] Pons has posted a great tutorial for anyone looking to hook their application into the Facebook Connect technology. This tutorial [...]
January 19th, 2010 8:28 pm
[...] Pons has posted a great tutorial for anyone looking to hook their application into the Facebook Connect technology. This tutorial [...]
January 20th, 2010 5:35 am
Hi Guys, Thats a nice post
January 21st, 2010 11:56 am
[...] This post was mentioned on Twitter by metoikos, onion_papa. onion_papa said: http://tinyurl.com/yaehohb Barattalo » Facebook Connect Tutorial [...]
January 25th, 2010 9:28 am
Hi. Please can you help me out. I am getting this error: Parse error: syntax error, unexpected T_INC in /home/gtownco/public_html/fbclogin.php on line 85
Thank you.
January 25th, 2010 10:07 am
yes. It’s missing a $. Change i++ with $i++.
there is also another errror in this line, I miss an “else”. Change the line this way:
I’ve fixed it in the post.
January 25th, 2010 11:38 am
Hi, can you please give an example for the settings-and-functions.php?
It would be great because I am new to PHP and do not know the syntax yet.
Thanking you in anticipation.
January 25th, 2010 12:13 pm
It’s just a file with at least those lines:
<? DEFINE("FB_API_KEY" , "value from facebook application setting"); DEFINE("FB_SECRET" , "value from facebook application setting"); function ConnectDB() { if (mysql_connect( "domain", "user", "pwd" ) && mysql_select_db( "yourdb" )) return 1; else return 0; } ?>you’re really a beginner!
January 25th, 2010 12:30 pm
Thanks! You are right, I’ve just written my first line of PHP code.
February 2nd, 2010 11:32 am
[...] Facebook Connect Tutorial [...]
February 2nd, 2010 2:39 pm
[...] Facebook Connect Tutorial Categories: webdev Tags: api, facebook Comments (0) Trackbacks (0) Leave a comment [...]
February 6th, 2010 9:17 am
Really great post and tutorial to integrate your web app with Facebook using Facebook Connect.
Keep it up.
February 7th, 2010 11:06 am
[...] Facebook Connect Tutorial [...]
February 7th, 2010 6:16 pm
[...] con FB Connect • Enlazar a fbclogin.php desde tu login • Otros puntos a seguir Enlace | Tutorial sobre Facebook Connect. /**/Peter OlleAutor de todas las cosas que se publican en este sitio, algunas interesantes y [...]
February 8th, 2010 9:15 pm
[...] Facebook Connect Tutorial [...]
February 8th, 2010 9:26 pm
[...] Barattalo | Facebook Connect Tutorial [...]