login.php

<?php

try {
        $app->post('/login', function () use ($app, $userModel) {
        if ( ! $userModel->login($_POST['username'], $_POST['password'])===true){
                throw new \Exception('Login failed, please check username/password and try again');
        }
        $app->redirect('/');
    });
} catch (\Exception $e) {
        // halts the app here
        $app->render('login.twig', array($e->getMessage()));
}