如何将外部Stripe库添加到我的symfony项目中？

Question

I'm trying to use Stripe with my Symfony projet. I have to add a php library.

To do that I use composer. I added to my composer.json:

"stripe/stripe-php": "3.*"

Then I have to add:

require_once('vendor/autoload.php');

To my Default controller, but it seems not to work.

Adding that next the uses of the controller, the error says:

Compile Error: main(): Failed opening required 'vendor/autoload.php' (include_path='.;C:\php\pear')

I think I miss something, but what?

Thanks Best regards