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Facebook::Graph::CookbUser:Contributed PeFacebook::Graph::Cookbook::Recipe1(3)

NAME
       Facebook::Graph::Cookbook::Recipe1 - Building Privileged	Applications

VERSION
       version 1.0801

DESCRIPTION
       Let's build a privileged	Facebook application from nothing.

   Things To Think About
       Though templating systems such as Template::Toolkit and web frameworks
       such as Dancer and content management systems such as WebGUI
       <http://www.webgui.org/>	are out	of scope for this document, when you
       build your own application, you should definitely consider using	them.

       For simplicity sake, in this recipe we'll be storing important
       information directly in the code. This is a terrible practice. Instead
       use a config file system	like Config::JSON to store your	settings.

   Assumptions
       This recipe assumes that	you know and have Plack	installed and that you
       have a Facebook (<http://www.facebook.com>) account.

       You'll also have	to be able to point a domain name to a server that is
       accessible from the Internet. DNS and server configuration are way
       beyond the scope	of this	document.

RECIPE
   Step	1: Set up the developer	application on Facebook.
       Go to <http://apps.facebook.com/developer>.

       Click "Allow".

   Step	2: Create your application.
       Go to <http://www.facebook.com/developers/createapp.php>	or click "Set
       Up New Application" from	the developer application.

       Fill in an application name. The	only restriction is that it can't use
       a Facebook trademark or be similar to official Facebook application
       names.

       Agree to	the terms of service.

       Click "Create Application".

   Step	3: The Connect tab.
       After creating your application,	go to the "Connect" tab.

       Fill in the "Connect URL" field.	It should be something like
       "http://www.yourapplication.com/facebook/". It is the base URL to where
       you'll be deploying your	application. The trailing slash	is required.

       Click "save".

   Step	4: Note	your application settings.
       You either want to make note of your "Application ID" and your
       "Application Secret" or bookmark	this page so you can come back to it.
       You'll need these later.

   Step	5: Create app.psgi.
       Create a	file called "app.psgi".	Start it off like this:

	use strict;
	use Plack::App::URLMap;
	use Plack::Request;
	use Facebook::Graph;
	use URI;

	my $urlmap = Plack::App::URLMap->new;

	# your code will go here

	$urlmap->to_app;

       All the code we have you	add should go in the "#	your code will go
       here" block, in the order that we have you add it.

   Step	6: Create your Facebook::Graph object.
       Now we can finally start	building Facebook::Graph into our app.

	my $fb = Facebook::Graph->new(
	   postback    => 'http://www.yourapplication.com/facebook/postback',
	   app_id      => 'Put Your Application	ID Here',
	   secret      => 'Put Your Application	Secret Here',
	);

       Now you need the	URL you	entered	in step	3, and the application ID and
       secret you got in step 4.

       On the end of the url, add "postback". This could be anything really,
       but it needs to be separate from	the Connect URL.

   Step	7: Create your application's connect page.
       Now we need to create the authorization redirect. This is where we tell
       Facebook	what permissions we want. There	is a complete list of
       permissions documented at
       <http://developers.facebook.com/docs/authentication/permissions>.

       If we only wanted basic permissions we can leave	the
       "extend_permissions" call out. But for this app let's say we want
       access to the user's email address and we want to be able to interact
       with the	user's account even when they aren't online.

	my $connect = sub {
	   my $env = shift;
	   my $request = Plack::Request->new( $env );
	   my $response	= $request->new_response;
	   $response->redirect(
	       $fb
	       ->authorize
	       ->extend_permissions( qw(email offline_access) )
	       ->uri_as_string
	   );
	   return $response->finalize;
	};

	$urlmap->map("/facebook" => $connect);

       We map the subroutine we	created	to "/facebook" because we'll likely
       have other things we want to display at "/". If we wanted to display
       something else at "/facebook" we	could have mapped this function	to
       "/facebook/authorize". It really	doesn't	matter what URL	we use here,
       all that	matters	is that	when we	want our users to authenticate against
       Facebook, this is the URL that we're going to send them to in our
       application.

   Step	8: Create the Facebook access token postback page.
       Our connect/authorization page will redirect the	user to	Facebook to
       authorize our app. Now we need to create	the page that the user will be
       redirected back to from Facebook. This is the "postback"	that we
       created in step 6.

	my $postback = sub {
	   my $env = shift;
	   my $request = Plack::Request->new( $env );

	   # turn our authorization code into an access	token
	   $fb->request_access_token($request->param('code'));

	   # store our access token to a database, a cookie, or	pass it	throuh the URL
	   my $uri = URI->new('http://www.yourapplication.com/search');
	   $uri->query_form( access_token => $fb->access_token );

	   my $response	= $request->new_response;
	   $response->redirect(	$uri->as_string	);
	   return $response->finalize;
	};

	$urlmap->map("/facebook/postback" => $postback);

       It's really stupid of us	to pass	our access token along the URL
       especially since	we requested "offline_access". We're only doing	it
       here to demonstrate the usage of	it. If you're requesting offline
       access, you should keep the access token	locked away in a secure
       database. If you	want to	pass it	along the URL, or store	it in a
       cookie, you should not request "offline_access".

   Step	9: Let's do something already!
       So now that we finally have an access token we can start	making
       privileged requests. That works like this:

	my $search = sub {
	   my $env = shift;
	   my $request = Plack::Request->new( $env );

	   # display a search
	   my $out = '<html>
	   <body>
	   <form>
	   <input type="hidden"	name="access_token" value="'. $request->param('access_token') .'">
	   <input type="text" name="q" value="'. $request->param('q') .'">
	   <input type="submit"	value="Search">
	   </form>
	   <pre>
	   ';

	   # display the results if a search is	made
	   if ($request->param('q')) {
	       $fb->access_token( $request->param('access_token') );
	       my $response = $fb->query
		   ->search($request->param('q'), 'user')
		   ->limit_results(10)
		   ->request;
	       $out .= eval{$response->as_json};
	       if ($@) {
		   $out	.= 'ERROR: '.$@->[1];
	       }
	   }

	   # close everything up
	   $out	.= '
	   </pre>
	   </body>
	   </html>
	   ';

	   my $response	= $request->new_response;
	   $response->status(200);
	   $response->content_type('text/html');
	   $response->body($out);
	   return $response->finalize;
	};

	$urlmap->map("/search" => $search);

   Step	10: Start the application and let's test this puppy out.
       On your server (the one that www.yourapplication.com points to) run the
       following command (assuming you're in the folder	with app.psgi).

	sudo plackup --port 80 app.psgi

       Now we point our	browser	to:

	http://www.yourapplication.com/facebook

       Voila! You have created an authenticated	Facebook app. If you would
       like to see this	full program check out "eg/recipe1.psgi" inside	this
       distribution of Facebook::Graph.

CAVEATS
       You should never	design an application using all	the poor stuff we've
       done here, like using a shared Facebook::Graph object, not using	a
       Framework/CMS or	at least Plack::Builder, not using a templating
       system, passing the offline access token	through	the URL, etc. We've
       made comments about these things	as we did them to warn you. These
       choices were made here only because this	is example code	who's primary
       purpose is to show you how to use Facebook::Graph, and not best
       practices for web development.

SEE ALSO
       For more	recipes, check out the Facebook::Graph::Cookbook.

LEGAL
       Facebook::Graph is Copyright 2010 - 2012	Plain Black Corporation
       (<http://www.plainblack.com>) and is licensed under the same terms as
       Perl itself.

perl v5.24.1			  2014-09Facebook::Graph::Cookbook::Recipe1(3)

NAME | VERSION | DESCRIPTION | RECIPE | CAVEATS | SEE ALSO | LEGAL

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