How to on Facebook wall using Graph API - facebook

Question

I have developed an application for facebook. I want that whenever any user add my application by clicking on allow permission dialog, a message is automatically posted on the users wall only for the first time.
<?php
include_once 'fb_sdk_212/src/facebook.php';
include_once 'config.php';
$flag_post=0;
$facebook = new Facebook(array(
'appId' => FACEBOOK_APP_ID,
'secret' => FACEBOOK_SECRET_KEY,
'cookie' => true,
'domain' => 'xxxxx.in'
));
$session = $facebook->getSession();
if (!$session) {
$flag_post=1;
$url = $facebook->getLoginUrl(array(
'canvas' => 1,
'fbconnect' => 0,
'req_perms' => 'email,user_birthday,status_update,publish_stream'
));
echo "<script type='text/javascript'>top.location.href = '$url';</script>";
} else {
try {
$uid = $facebook->getUser();
$me = $facebook->api('/me');
$updated = date("l, F j, Y", strtotime($me['updated_time']));
echo "Hello " . $me['name'] . "<br />";
echo "You last updated your profile on " . $updated."<br/>";
if($flag_post == 1){
# let's check if the user has granted access to posting in the wall
$api_call = array(
'method' => 'users.hasAppPermission',
'uid' => $uid,
'ext_perm' => 'publish_stream'
);
$can_post = $facebook->api($api_call);
echo $can_post;
$attachment = array(
'name' => 'Tracer',
'description' => 'xxxx',
'caption' => 'xxxxx',
'picture' => 'images/mt75.jpg',
'link' => 'tracer/'
);
if($can_post){
# post it!
$facebook->api('/'.$uid.'/feed', 'post', $attachment );
echo 'posted';
} else {
die('Permissions required!');
}
}
} catch (FacebookApiException $e) {
echo "Error:" . print_r($e, true);
}
}
?>

Answer 1

Well you need to get publish_stream extended permission.
http://developers.facebook.com/docs/authentication/permissions
This can be done in the permission dialog
http://developers.facebook.com/docs/reference/javascript/FB.login
by adding publish_stream to the perms list.
After that you will be able to publish to the user's wall at any time.

Answer 2

I would do one of the following:
Add a field in a database table to indicate that it has been done. Then just check if it has been set. If cookies are enabled on the users PC you could use but using a database would be best.
Get the user to take an action to do the post. So it requires a user action. This has the disadvantage that some users may not do it.

Answer 3

I feel like you can handle this fairly easily without Facebook being involved in decision to publish to the users wall or not. In your database's user table you should have a column for first_fb_post. When a user account is created it should default to 0, then once you publish the wall post it should be updated to 1.
And your facebook publish function would be set like:
if($first_fb_post == 0)
{
//your FB publishing code here
//update your user table to mark this users first_fb_post to 1
}

Answer 4

You could hook into the first time the user "installs" your app. When they do this they are redirected to your site with a get parameter of 'code' set in the url:
if(isset($_GET['code'])){
// User Authorized app. Lets hook the install event.
if($can_post){
# post it!
$facebook->api('/'.$uid.'/feed', 'post', $attachment );
echo 'posted';
} else {
die('Permissions required!');
}
}