Code snippet that can help you to call a controller function in a module in Drupal 8.
Example:
namespace Drupal\mymodule\Controller;
use Drupal\Core\Controller\ControllerBase;
class ContentController extends ControllerBase {
public function content() {
return "hello world";
}
}
If you want to use a controller class in a hook, create an instance of the controller and use the method of that instance:
use Drupal\mymodule\Controller\ContentController;
$contentController = new ContentController();
$content = $contentController->content();
