How to autopost to facebook page with app id - facebook

Question

How to post to Facebook page with the App ID & Secret & Page ID without need to login with the user Admin of the page to get access token, the App owner who is the Admin of the page shouldn't be enough to auto post !?
I am using PHP & SDK4 of Facebook API.

Answer 1

You can´t post anywhere on Facebook without authorizing. If you want to post "as Page", you need to authorize a Page admin with the "publish_pages" permission and use a Page Token. You can´t get a User or Page Token without authorization, and of course you can´t automate the authorization process. Check out the docs for detailed information: https://developers.facebook.com/docs/graph-api/reference/v2.3/page/feed#publish
You will also need to learn about Access Tokens:
https://developers.facebook.com/docs/facebook-login/access-tokens
http://www.devils-heaven.com/facebook-access-tokens/

Answer 2

In fact all i wanted specifically to have permanent page access token so i can auto post forever without requiring authentication from the user each time for posting.
follow these steps to get it: Permanent Access Token
then use auto post code :
session_start();
define('FACEBOOK_SDK_V4_SRC_DIR', 'facebook-php-sdk-v4-4.0-dev/src/Facebook/');
require __DIR__ . '/facebook-php-sdk-v4-4.0-dev/autoload.php';
use Facebook\FacebookSession;
use Facebook\FacebookRequest;
use Facebook\GraphUser;
use Facebook\FacebookRequestException;
use Facebook\FacebookRedirectLoginHelper;
// Facebook App
$api_key = 'xxxxxxxxxxxxxxxx'; //App ID
$api_secret = 'xxxxxxxxxxxxxxxx'; //App Secret
$page_id = 'xxxxxxxxxxxxxxxx'; //Page ID
$page_token = 'from the steps in the url';
$fb_post = array(
'message'=> 'test message',
'name'=> '',
'link'=> 'http://www.example.com/',
'picture'=> 'http://www.example.com/image.jpg',
'caption'=> '',
);
// start a session for this App
FacebookSession::setDefaultApplication($api_key, $api_secret);
try {
$session = new FacebookSession($page_token);
} catch(FacebookRequestException $e) {
die(" Error : " . $e->getMessage());
} catch(\Exception $e) {
die(" Error : " . $e->getMessage());
}
try {
// Auto posting
$page_post = (new FacebookRequest( $session, 'POST', '/'. $page_id .'/feed', $fb_post))->execute()->getGraphObject()->asArray();
// return post_id, optional
print_r( $page_post );
} catch (FacebookRequestException $e) {
// The Graph API returned an error
echo '<b style="color:blue;">'.$e->getMessage().'</b>';
} catch (\Exception $e) {
// Some other error occurred
echo '<b style="color:red;">'.$e->getMessage().'</b>';
}