Create a Facebook Application With PHP

Facebook Is The New Black

Everyone is talking about Facebook and their new Application Platform:

And I have to admit I think itï¿½s pretty cool too. So I decided to
create an application that uses the Facebook Platform. Iï¿½m writing the
application in PHP and I thought it might be useful for others to know
how to write their own Facebook PHP applications. So here we are.

What Will I Learn?

I will cover the basics of using the Facebook PHP library and how to get your application started, including:

Installing The Facebook Developer Application
Downloading The Facebook PHP Client Library
Creating Your Application
Hello Facebook! Example
FBML – Facebook Markup Language
Using the Facebook API

Getting Started As A Facebook Developer

The first thing you need of course is a Facebook account. You can sign up for Facebook at www.facebook.com.
Once you have your account you’ll need to install the Facebook
developer application. This little tool will allow you to generate your
application profile and get an API key (more on that later). Once
you’ve logged into Facebook visit: www.facebook.com/developers/ or
click below to install the developer application:

Add The Facebook Developer Application.

PHP Facebook API Client Library

Facebook has created a nice php library that allows you to use their
API without writing a lot of extra code. You can grab the PHP version
of the library at developers.facebook.com/resources.php. Download the ‘PHP (4 and 5) Client Library’.

Once you’ve downloaded the library unzip it into a folder that is
accessible by your PHP scripts. So you would have something like
/php_include_directory/facebook/ and in that folder you will have the
entire Facebook PHP Client Library (3 folders: client, footprints,
php4client). I’m using PHP5 so my examples will be using the “client”
directory of the library. The footprints folder is an example
application.

Creating Your Application Profile And API Key

Facebook requires that you register each application you make. Once you’ve logged into Facebook and installed the developer application go to the developer panel (or click here). Inside the developer application click “Set Up New Application”.

Choose a name for your application. This is
important because it’s what users will see when they are browsing the
application directory. Currently the name field is the only thing used
when searching for applications. So it’s doubly important at this point.

Click on “Optional Fields”. Then fill out the Callback Url with the location of your script. This is the public URL on your webserver where the Facebook application will be.

Next fill out the “Canvas Page URL”. This is your
application URL within Facebook. For example if the application was
called “Makebeta Is Cool” then the application URL could be: “makebeta”
which would make the full URL: http://apps.facebook.com/makebeta/.

Check Yes for Can your application be added on Facebook?

You should check the Developer Mode checkbox so that no one can add your application until you are done working on it.

Under Integration Points fill out Side Nav URL
with the full Canvas Page URL. In the example above it would be
http://apps.facebook.com/makebeta/. This allows users to add your
application to their Facebook left side bar navigation.

All of these settings can be changed after the application has been created. But it’s a good idea not to change the Canvas Page URL or Name once you have users that have installed your application.

Further Reading: Starting your First Facebook App: Demystifying Application Form Field by Field

Get the API Key and Secret. You should now see your application listed with a unique API Key and Secret code. You’ll use these within your application.

Hello Facebook!

Let’s create a really simple first application that just says hello
to the current Facebook user. Here’s the code for the Hello Facebook!
application:

<?php/* include the PHP Facebook Client Library to help  with the API calls and make life easy */require_once('facebook/client/facebook.php');

/* initialize the facebook API with your application API Key  and Secret */$facebook = new Facebook(YOUR_API_KEY,YOUR_SECRET_CODE);

/* require the user to be logged into Facebook before  using the application. If they are not logged in they  will first be directed to a Facebook login page and then  back to the application's page. require_login() returns  the user's unique ID which we will store in fb_user */$fb_user = $facebook->require_login();

/* now we will say:  Hello USER_NAME! Welcome to my first application! */?>

Hello <fb:name uid='<?php echo $fb_user; ?>' useyou='false' possessive='true' />! Welcome to my first application!

<?php

/* We'll also echo some information that will  help us see what's going on with the Facebook API: */echo "<pre>Debug:" . print_r($facebook,true) . "</pre>";

?>

So what happens when a user hits the Canvas Page URL (from the example it would be: http://apps.facebook.com/makebeta/)? The require_login() call will produce a screen like this for the user:

If you change require_login() to require_add() the user will get a page that looks like this:

After the user logs into or adds the application they will get the
canvas page with the “Hello…” text. It should look something like this:

Facebook Markup Language – FBML

Facebook has provided a bunch of built in tags that will render dynamic
data inside your application. All you have to do is include the tags
with the correct parameters. In the example above the fb:name tag is used to generate the user’s name on the canvas page. fb:name has a couple of parameters, one of which is uid.
In the example above we set uid = $fb_user which is the unique ID of
the current user. There are lots of FBML tags you can use, check them
all out at: developers.facebook.com/documentation.php?doc=fbml

Facebook API REST-based Interface

The Facebook Client Library provides you with an easy to use wrapper
for the Facebook API REST interface. All of the API calls are available
under the $facebook->api_client object (after you initiate the
$facebook object). Many of the calls will require that the user has
either added or logged into the application. Here’s an example call
that would retrieve the user’s About Me text from their profile:

$fb_user = $facebook->user;$about = $facebook->api_client->users_getInfo($fb_user,'about_me');

There are a number of API calls, and a list of them can be found here:
developers.facebook.com/documentation.php

Resources and Further Reading

These are very helpful pieces of information that I highly recommend
reading before you get too far into making your Facebook application.

And of course the official documentation / developer site:

Other Facebook tutorials and how-to articles:

About the author

Written by Justin Laing.

Justin is the chief software architect for MerchantOS, a company that provides web based point of sale and inventory control to small retailers.

Website

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