Silex - get right condionals in finish middleware - symfony

Question

I want to create a pdf file out of some route-dependant data
{http://example.com/products/123/?action=update}
$app->finish(function (Request $request, Response $response) {
// Make a pdf file, only if:
// - the route is under /products/
// - the action is update
// - the subsequent ProductType form isSubmitted() and isValid()
// - the 'submit' button on the ProductType form isClicked()
});
As a normal form submission process I have:
public function update(Application $app, Request $request)
{
$form = $app['form.factory']->create(ProductType::class, $product);
$form->handleRequest($request);
if ($form->isSubmitted() && $form->isValid()) {
if (!$form->get('submit')->isClicked()) {
return $app->redirect('somewhere');
}
$product = $form->getData();
$app['em']->persist($product);
$app['em']->flush();
return $app->redirect('product_page');
}
return $app['twig']->render('products/update.html.twig', array(
'form' => $form->createView(),
));
}
Questions:
Should I duplicate all of the conditionals in finish middleware?
How to access the Product entity in finish middleware?
Consider having multiple resource types like Products, Services, Users, ...