php - Troubleshooting composer: classes not autoloading with CodeIgniter 3 -

problem

i trying use paypal checkout rest sdk requires paypal library autoloaded through composer. have gone through steps enable composer in codeigniter 3 when go controller autoloading paypal\rest\apicontext class following error:

fatal error: class 'paypal\rest\apicontext' not found in c:\xampp\htdocs\php\toucan-talk\app\modules\paypal\controllers\paypal.php on line 15

what have far

here composer.json file

{     "require": {         "paypal/rest-api-sdk-php" : "*"     } } 

i have set $config['composer_autoload'] = true; in config.php file.

here controller

<?php  use paypal\rest\apicontext;  class paypal extends mx_controller {     public function __construct()     {         $api = new apicontext(          );         var_dump($api);     }  } 

question

how troubleshoot composer , autoloader can pinpoint autoload process failing.

well here solution: in config.php instead of setting...

$config['composer_autoload'] = true;  

you need put

$config['composer_autoload'] = fcpath . 'vendor/autoload.php';  

however still not why works opposed original documentations recommendation. bit of headache really.