Zend Framework 2 - handling form actions

In Zend Framework 2, I've created a class that extends Zend\Form\Form called MyForm.

In the indexAction of one Controller class, I'll initialize MyForm like this:

 public function indexAction()
 {
     $form = new MyForm('my-name');
     $viewModel = new ViewModel(array('form' => $form));
     return $viewModel;
 }

Then in the corresponding view, I basically just do

$form = $this->form;
$form->prepare();

echo $this->form()->openTag($this->form);
echo $this->formCollection($form);
echo $this->form()->closeTag();

This all works, but you may have noticed that the action for the form is missing.

I have tried to add the action like this in the view:

$form->setAttribute('action', $this->url(NULL, array('controller'=>'Index', 'action' => 'go')));

Then in the go action inside my IndexController I just have this for testing:

    public function goAction()
    {
        die('huh');
    }

This did not work at all, I always land at the form view (== index action) again. Why is the go action never executed?

I also know that I could either hardcode the action attribute and let a segment route handle the processing, or I could even define an own route for that.

In what cases form actions should get their own route?
In what cases form actions should be handled using a segment route?
In what cases form actions should be handled like in my example?

If there are no hard rules for this: What intention do the different approaches communicate?

Is it also possible to add form actions in the controller instead of the view?

Continuing on from the comments: That's not how the URL helper works - if you omit the first parameter, the current route is used instead. That's probably why you're not getting the form action you expect.

Personally, I always specify the route name when using the URL helper - makes things clearer.