Facebook Graph API cookbook page

Working with the Graph API

Overview

The graph API is a collection of RESTful web services facebook provides. Using the graph api, you can publish, interact with or create almost anything in facebook. Developers make GET, POST and DELETE requests to different parts of https://graph.facebook.com. These requests can require an access token, which grants read/write privileges.

Facebook provides a tool at https://developers.facebook.com/tools/explorer that lets users generate access tokens for their account with any combination of permissions and make graph api calls. Try using this tool to interact with your facebook accounts. You can read facebook’s graph api documentation here: https://developers.facebook.com/docs/reference/api/

Body

GETing https://graph.facebook.com/1206427506 (my facebook user id) with no access token returns this JSON:
{
 "id": "1206427506",
 "name": "Paul Kinsky",
 "first_name": "Paul",
 "last_name": "Kinsky",
 "link": "https://www.facebook.com/people/Paul-Kinsky/1206427506",
 "gender": "male",
 "locale": "en_US",
 "type": "user"
}

The same call with an access token granting the user_about_me privilege to my account returns this JSON:
{
 "id": "1206427506",
 "name": "Paul Kinsky",
 "first_name": "Paul",
 "last_name": "Kinsky",
 "link": "https://www.facebook.com/profile.php?id=1206427506",
 "hometown": {
   "id": "113001432047882",
   "name": "Wareham, Massachusetts"
 },
 "location": {
   "id": "105596609473837",
   "name": "Worcester, Massachusetts"
 },
 "gender": "male",
 "timezone": -5,
 "locale": "en_US",
 "languages": [
   {
     "id": "113301478683221",
     "name": "American English"
   }
 ],
 "verified": true,
 "updated_time": "2011-11-02T16:50:18+0000",
 "type": "user"
}




The facebook php sdk handles graph api calls with the Facebook::api() method.

$facebook->api('/me/feed', 'POST',
                                   array(
                                     'link' => 'www.example.com',
                                     'message' => 'Posting with the PHP SDK!'
                                ));

Graph API reference:

https://developers.facebook.com/docs/reference/api/user/#posts

Components:

1. $facebook
1. a Facebook object initialized with your application’s APP_ID and APP_SECRET
2. '/me/feed'
1. the part of the facebook graph api to contact
2. in this case, the feed of the current user
3. ‘POST’
1. the type of request
2. in this case, we’re POSTing to the current user’s feed
4. array(...)
1. parameters specific to the graph api call
2. in this case, we’re posting a link to 'www.example.com' and the message that we’re 'Posting with the PHP SDK!' to the currently logged in user’s feed, or news feed.

Here’s an example using this code from facebook’s documentation:


Example code

<?
 // Remember to copy files from the SDK's src/ directory to a
 // directory in your application on the server, such as php-sdk/
 require_once('php-sdk/facebook.php');

//These parameters can be viewed when you create your test app here: //https://developers.facebook.com/apps
 $config = array(
   'appId' => 'YOUR_APP_ID',
   'secret' => 'YOUR_APP_SECRET',
 );

 $facebook = new Facebook($config);
 $user_id = $facebook->getUser();
?>
<html>
 <head></head>
 <body>

 <?
   if($user_id) {

     // We have a user ID, so probably a logged in user.
     // If not, we'll get an exception, which we handle below.
     try {
       $ret_obj = $facebook->api('/me/feed', 'POST',
                                   array(
                                     'link' => 'www.example.com',
                                     'message' => 'Posting with the PHP SDK!'
                                ));
       echo '<pre>Post ID: ' . $ret_obj['id'] . '</pre>';

     } catch(FacebookApiException $e) {
       // If the user is logged out, you can have a
       // user ID even though the access token is invalid.
       // In this case, we'll get an exception, so we'll
       // just ask the user to login again here.
       $login_url = $facebook->getLoginUrl( array(
                      'scope' => 'publish_stream'
                      ));
       echo 'Please <a href="' . $login_url . '">login.</a>';
       error_log($e->getType());
       error_log($e->getMessage());
     }   
     // Give the user a logout link
     echo '<br /><a href="' . $facebook->getLogoutUrl() . '">logout</a>';
   } else {

     // No user, so print a link for the user to login
     // To post to a user's wall, we need publish_stream permission
     // We'll use the current URL as the redirect_uri, so we don't
     // need to specify it here.
     $login_url = $facebook->getLoginUrl( array( 'scope' => 'publish_stream' ) );
     echo 'Please <a href="' . $login_url . '">login.</a>';

   }

 ?>      

 </body>
</html>

Facebook Auth cookbook page

Facebook Authentication

Overview

Most actions on Facebook require some sort of authentication token. For example, sending a request for information about a user without the relevant auth token returns only their public information: name, user id, and a few other fields. However, a request with the proper token can GET several pages of JSON describing a user who’s authorized the requesting app.

Body

There are several ways to acquire such a token, but we will be focusing on a simple method using the PHP SDK. Complete documentation can be found here.

First, working with the PHP SDK requires initializing an instance of the Facebook object with your App_ID and App_Secret. These values are unique to each app, and can be thought of as you username and password.

The Facebook::getLoginUrl(params) method generates a url that takes the user to a facebook dialouge where the user is asked if they would like to grant your application the permissions specified in params, after which the user is redirected to either a url specified in params or the originating page

From the documentation:

$params = array(
  scope => 'read_stream, friends_likes',
  redirect_uri => 'https://www.myapp.com/post_login_page'
);

$loginUrl = $facebook->getLoginUrl($params);

the scope parameter can be any of these permissions. Remember that requesting unnecessary permissions will make users suspicious.

The auth token obtained is temporary, meaning that this method can only be used when the user is online or shortly after.

There is also a Facebook::getLogoutUrl() method, see the example below for a full example (source)

Example Code

<?
 // Remember to copy files from the SDK's src/ directory to a
 // directory in your application on the server, such as php-sdk/
 require_once('php-sdk/facebook.php');

 $config = array(
   'appId' => 'YOUR_APP_ID',
   'secret' => 'YOUR_APP_SECRET',
 );

 $facebook = new Facebook($config);
 $user_id = $facebook->getUser();
?>
<html>
 <head></head>
 <body>

 <?
   if($user_id) {

     // We have a user ID, so probably a logged in user.
     // If not, we'll get an exception, which we handle below.
     try {

       $user_profile = $facebook->api('/me','GET');
       echo "Name: " . $user_profile['name'];

     } catch(FacebookApiException $e) {
       // If the user is logged out, you can have a
       // user ID even though the access token is invalid.
       // In this case, we'll get an exception, so we'll
       // just ask the user to login again here.
       $login_url = $facebook->getLoginUrl();
       echo 'Please <a href="' . $login_url . '">login.</a>';
       error_log($e->getType());
       error_log($e->getMessage());
     }   
   } else {

     // No user, print a link for the user to login
     $login_url = $facebook->getLoginUrl();
     echo 'Please <a href="' . $login_url . '">login.</a>';

   }

 ?>

 </body>
</html>

Associating facebook and ASM accounts

Here's how it's done:

http://developers.facebook.com/docs/plugins/registration/
This pops up an iframe that has in it a form prefilled with your facebook data. It also supports custom fields. You can fill out or change any fields you want to and then submit the form as a signed request to the server.

If a user only has a Facebook account, they can just register with this to create an associated ASM account.

When an ASM account is already logged in, we should be able to use the same form with different parameters to associate the two accounts.

Edit: Code is here: http://pkinsky.com/register.html

Share pages with friends

 Like shares with all, send allows you to choose recipients from among your friends.

http://www.pkinsky.com/askhelp.html

API progress

As of now, I've made a test api call that gets a database object, saves data to it, and then reads other data from it. I've also managed to create 'watcher' database objects via API and retrieve data from them (a callback url) elsewhere.

The next step is to send a POST request to that callback_url when the relevant event happens. This can be expanded to cover assignments being added, achievements, etc.

EDIT: and then I uploaded the code - my api call is test_call in lib/gwt/ajax.rb

EDIT2: now featuring working post/response of JSON data to and from an external php script! Proof of concept finished, time to start on the actual product.

Assistments API finally working

I just got my hello world assistments api call working. Awesome.

Source Code and Documentation

First, I want to say that I’ve open-sourced LcAlg, my program for generating laser-cut polygonal sculptures from 3d models. There’s a link a little bit farther down on the page if that’s what you came here for.

Second, the majority of this post will be about an interesting method of connecting coroplast sheets using acrylic connectors that I’ve developed.

Source Code

svn co https://lcalg.svn.sourceforge.net/svnroot/lcalg lcalg    

https://sourceforge.net/projects/lcalg/files/

1. Check out the code. Download either of the two obj files and put them in the input folder.

2. Adjust constants in util.constants.py to change most values in the program. Currently it’s set to use 2.5mm acrylic and ~3.5mm coroplast.

3. Run LcAlg by running LcAlg.py. You’ll need python 2.7.

4. Watch for updates. This is an early beta that I’ll be updating regularly.

Connectors

Coroplast is essentially plastic cardboard. It is lightweight and flexible, and bends rather than breaking. I now use it for the triangles, or faces, in my models.

I used to use acrylic plates for both the faces and the connectors. It was shatter-prone, heavy and expensive. I secured the faces to the connectors with first solvent glue and then cotter pins. This worked, but was labor intensive and in some cases fragile.

The solution is to use acrylic connectors and coroplast sheets. This leverages the strength of both materials. Because the coroplast is flexible, I use retaining tabs - the coroplast deforms around the rigid acrylic tabs and is locked into place

This forms a very strong connection. I have to pull very hard to force the pieces apart. However, I can easily remove a connector by slipping the retaining tabs over the coroplast retainer. Think zip ties - all it takes is a small piece of metal to jimmy one open but brute force will get you nowhere.

(By vector-cut I mean vector-etched)

Unfortunately, sharp angles lead to an issue that can be seen in this diagram: if angle A increases much more, distance B will decrease until there is not enough material there to hold the connector together

Large angle A’s can also lead to intersecting faces: In the diagram below, imagine if angle A were to increase. The two coroplast panels would quickly be intersecting. LcAlg solves this issue by calculating an offset and then removing that much material from the relevant edge.

Faces

A face is a flat coroplast triangle with 3 pairs of two mounting points for the acrylic connectors.

They’re cut out as below, to save laser time and material.