anche PHP ha i suoi momenti

gistfile1.php

$app->get('/admin/print/{course_id}/{generated}', function ($course_id, $generated) use ($app) {
    $query = $app['idiorm']->getTable('keys')
        ->select('code')
        ->where('course_id', $course_id)
        ->where('generated', $generated);

    $stream = function () use ($query) {
        $out = fopen('php://output', 'w');
        foreach ($query->find_array() as $key) {
            fputcsv($out, $key);
        }
        fclose($out);
    };

    return $app->stream($stream, 200, array(
        'Content-Type'        => 'text/csv',
        'Content-Disposition' => 'attachment; filename="Course'.$course_id.'_'.$generated.'.csv"'
    ));
})
->bind('print');